Book - Handbook of Pathological Anatomy 2.6
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Meckel JF. Handbook of Pathological Anatomy (Handbuch der pathologischen Anatomie) Vol. 2. (1812) Leipzig.
- Ligaments: I. Trunk | II. Head | III. Extremities Muscles: I. Trunk | II. Head | III. Extremities Angiology: I. Heart | II. Body or Aorta Arteries | III. Body Veins| IV. Pulmonary Artery | V. Pulmonary Veins | VI. Lymphatic System | VII. A Comparison of Vascular System Nervous System: I. Central Nervous System
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Section III. Of the Muscles of the Extremities
§ 1 105. The muscles of the extremities form the greater part of these sections of the body. Most of them have a more or less elongated form and assume a longitudinal direction, although this is not the direction of their fibres, which go obliquely from one or more edges to the tendons. Very few of them have a transverse direction or one intermediate between it and the preceding : the latter are shorter.
The muscles which follow the longitudinal direction flex and extend the different parts of the limbs ; the transverse and the oblique separate them from each other or turn them on their axes.
The muscles of both extremities are surrounded with general tendinous sheaths ( fascia! aponeuroticœ) and the tendons of the inferior, which are the longest in proportion, and are firmly attached in several places by strong fibrous ligaments to the bones over which they pass.
In regard to situation, arrangement, and number, they correspond perfectly in their essential particulars, and differ only in modifications dependent on the different functions of the two limbs.
Chapter I. Muscles of the Upper Extremities
§ 1106. The muscles which move the first section of the bones of the upper extremity, or the bones of the shoulder, all come from the bones of the trunk, from which arise also some of those which move the bone of the second section — the humerus. The former are the trapezius, the rhomboidei, and the levator anguli scapulæ ; the others the pectoralis major and the latissimus dorsi muscles, which have already been described (§ 1001).
It is convenient to commence the description of these muscles by that of their common aponeurotic sheath.
1. Of The Aponeurotic Sheath of the Upper Limbs
§ 1107. The muscles of the upper extremities are surrounded by a tendinous envelop called the brachial aponeurosis (fascia brachialis).
This arises in very muscular subjects from the deltoid muscle, but
sometimes we do not see it except below this muscle. It is always
stronger on the fore-arm than on the arm. However, at the posterior
part of the anterior and posterior faces it is always much thicker than
on the other faces and strengthened by transverse and oblique fibres,
which cover the longitudinal fibres externally.
In most of its extent it envelopes the muscles externally only. However, at the lower end of the arm, in the inner angle, there is a triangular slip, the internal and external intermuscular ligament ( L . intermuscular e internum et externum ), which leaves the aponeurosis and goes forward. The external extends from the outer condyle to the upper extremity of the projecting part of the anterior angle ; the internal from the inner condyle to the corresponding point of the inner angle. They extend between the extensors and flexors of the fore-arm and increase their surfaces of attachment.
Two similar but much weaker ligaments are also found in the forearm in a similar situation. They separate the flexors and the extensors, both on the ulnar and radial side ; because they proceed from the inner face of the aponeurosis to the posterior edge of the ulna and of the radius to which they are attached.
Near the lower end of the fore-arm, the transverse fibres disappear, or at least become evidently thinner ; but they again accumulate on the end of its posterior face and on the back of the thumb, become much more thick than high, and give rise in this place to the dorsal ligament of the carpus ( Lig . carpi dorsale , s. armillare ).
This ligament extends from the transverse process of the radius to the small head of the ulna, the pisiform, and the tuberosity of the fifth metacarpal bones. It is formed at its upper part, which is the weakest, of transverse fibres, which descend from the ulna to the radius, and at the lower part of fibres, which go backward and downward from the radius, and consequently partially cross the preceding.
Under it pass the tendons of the abductor magnus and extensor pollicis, the radiales externi, the extensor digitorum communis, the extensor indicis proprius, the extensor minimi digiti proprius, and the ulnaris externus muscles. Their passage is facilitated by the partitions which descend from the inner face of the ligament to the asperities on the ends of the bones of the fore-arm and divide it into six parts.
The first, the anterior,, extends from the anterior edge of the lower end of the radius to the first asperity on the back of this bone, and contains the tendons of the abductor pollicis longus and of the extensor pollicis brevis muscles.
Through the second, which is larger and which extends from the first dorsal asperity to the second, pass the tendons of the two radial© externi muscles.
The third, a little oblique forward and downward, extends from tin second to the third dorsal asperity of the radius, to the posterior edge of its lower extremity, and lodges the tendon of the extensor pollids longue muscle.
The fourth, the largest, extends from the third dorsal eminence to the posterior edge of the radius, and receives the tendons of the extensor digitorum communis and extensor proprius indicis muscles.
The fifth, the smallest, is comprised between the radius and the anterior edge of the small head of the ulna ; it receives the tendon of the extensor minimi digiti proprius muscle.
Finally, the sixth, which extends from the posterior edge of the small head of the ulna to its styloid process, embiaces the tendon of the ulnaris externus muscle.
The lower edge of this ligament, which should be regarded not as a separate ligament but only as the development of the brachial aponeurosis, is uninterruptedly continuous with the aponeurosis of the back of the hand, which gives a loose common envelop to the tendons of the extensor muscles, blends with the oblique tendinous fibres by which the tendons of the extensors of the fingers are retained in place, and concurs to form them.
The brachial fascia is also strengthened at the lower part of the anterior face of the fore-arm and on the palmar side of the carpus.
The upper part of this portion, which is the feeblest and which extends from the anterior edge of the radius to the pisiform bone, forms the common palmar ligament of the carpus ( Lig . carpi velar e commune). It unites at its ends with the dorsal ligament. Under it pass the tendons of the flexors of the fingers, and in a special sheath that of the radialis internus.
The lower part, which is much stronger, forms the proper palmar ligament of the carpus {Lig- carpi volare proprium). This ligament is formed by transverse and oblique fibres. Above, it blends in great part with the preceding. Below, it strengthens the palmar aponeurosis. Its two edges arise from the palmar eminences of the carpus, which are formed on the radial side by the trapezium and the pyramidal bones and on the ulnar side by the pisiform and unciform bones.
2. Muscles of the Shoulder
§ 1108. The muscles of the shoulder, which surround the scapula and which extend from this bone and also from the clavicle to the humerus, are the deltoides, the supraspinatus, the infraspinatus, the teres major, the subscapularis, the teres minor, and the coraco-brachialis muscles.
I. deltoïdes, or the extensor of the arm.
§1109. The deltoides muscle, Sus-acromio-humeral, Ch. {M. deltoïdes , levator , attollens humeri), is a very strong muscle, which occupies the upper and anterior part of the region of the shoulder. It arises by its upper longest and concave edge from the anterior edge of the scapular end of the clavicle, from the anterior edge of the acromion process, and from the lower edge of all the spine of the scapula at its anterior part, by fibres almost entirely fleshy or which at least have very short tendons, and by very long tendinous fibres at its posterior.
After leaving this point, the muscle gradually becomes thicker, goe3 downward, and terminates by a fleshy summit externally, but possessing within a very long tendon, which is attached directly below the tendon of the pectoralis major muscle, at the posterior end of the external linea aspera, which arises from the outer tubercle of the humerus and at the central part of the outer face of this bone, which presents in this place a triangular impression.
These fibres converge from above downward ; so that the central are straight, the anterior oblique from before backward, and the posterior from behind forward.
In examining this muscle more attentively, we recognize that it is composed of two orders of triangular fasciculi. The first order contains four fasciculi, which are larger than the others and the bases of which are turned upward and their summits downward. Between are the three smaller fasciculi of the second order, which are broader below than above but the two ends of which are a little narrower than the central part.
Below the upper edge of this muscle, between it and the capsular ligament, we find a considerable mucous bursa, which corresponds usually to the acromion, extends between this last process and the proper anterior ligament of the shoulder, and sometimes divides into two bursæ, one of which is situated near the coracoid process.
The deltoid muscle raises the arm and separates it. from the side of the body.
§ 1110. A remarkable analogy -with the structure of the mammalia is the existence of a posterior slip, entirely distinct from the rest of the muscle, which we have found several times. This slip arises from the tendinous expansion of the infraspinatus muscle (§ 1112), and from the centre of the inner edge of the scapula, by a broad and thin tendon, and is attached to the tendon of the deltoides. In most mammalia, in fact, the deltoides divides into a clavicular and a scapular portion and the latter is subdivided into an acromial and a spinous portion.
We more frequently find the posterior part of the muscle simply separated from the anterior. We ought also to place among these anomalies the existence of a head, which goes from the anterior edge of the scapula to the deltoides,(l) and which is still more analogous â– with a part of the deltoides in birds.
(1) Albinus, p. 422.
II. ROTATORS OUTWARDLY.
I. SUPRASPINATUS.
§ 1111. The supraspinatus muscle, Petit susse upvlo-trochitcriev Ch., is a triangular muscle which fills the supraspinal fossa, and is formed of fibres which converge from behind forward, from below upward, and from within outward. At first it is rather thick, but gradually becomes thinner. It arises from all the supraspinal fossa, from that part of the posterior edge of the scapula situated above the spine, and from the posterior part of the upper edge and also from the upper face of this spine. It changes under the acromion process, directly below the large proper ligaments of the scapula, into a short and strong tendon, which, passing below the capsular ligament of the scapulo-humeral articulation, which it contributes to strengthen, goes to attach itself to the upper and inner part of the outer tubercle of the humerus.
This muscle turns the arm outward and raises it,
II. INFRASPINATUS.
§ 1112 . The infraspinatus muscle, Grand susscapido-trochiterien , Ch., arises from all the infraspinal fossa of the scapula, except its lower part. It goes outward and forward, so that its upper fibres are transverse, and the lower become more oblique forward and upward the lower they are. Its thickness gradually increases as it proceeds outwardly and it terminates in a strong tendon, which extends farther on the posterior than on the anterior face. This tendon adheres to the capsular ligament of the shoulder which it strengthens, blends above with that of the preceding muscle, and is attached to the central part of the outer tubercle of the humerus.
We find a large mucous bursa between the scapula and this tendon.
This muscle draws the humerus backward and downward, and rotates it from within outward.
III. TERES MINOR.
§ 1113. The teres minor muscle, Plus petit susscapulodrochiterien, Ch. is quadrangular, and is scarcely distinguished from the preceding. It arises from the central part of the posterior lip of the anterior edge of the scapula, and goes directly before the lower and anterior edge of the infraspinatus muscle forward, outward, and downward, where, gradually becoming narrower but thicker, it terminates by a short and strong tendon at the lower part of rhe outer tubercle of the humerus, and at the outer ridge of the humerus which descends from this tubercle.
It acts like the preceding, but it draws the humerus more outward
IV. ROTATORS INWARD.
SUB-SCAPÃœLARIS.
§ 1114. The subscapularis muscle, sous-scapulo-trochinien , Ch., the strongest of the two muscles which turns the humerus on its axis inward, occupies all the lower face of the scapula. Its upper fibres descend obliquely outward and forward, the central are transverse, and the inferior are very oblique from behind forward and from within outward. It gradually contracts to a considerable degree, passes behind the upper end of the coraco-brachialis, and the shoit head of the biceps muscle, and terminates in a short, flat, and thick tendon, which is attached to all the circumference of the inner tubercle of the humerus.
Its structure is very complex, and we may reduce it to two orders of fasciculi which are more or less evidently distinct. The first, commonly five in number, arise by a tendinous summit along the inner lip of the posterior edge, and the asperities which are found on the anterior face of the scapula. The lower, which is also the strongest, forms the lower and outer part of the muscle. All progressively enlarge, and are attached to the upper tendon.
We find the second layer between them ; this also is formed of five fasciculi, of which the upper likewise forms the upper part of the muscle. These fasciculi are generally stronger and broader externally, and pointed inwardly. They come from the spaces between the eminences, whence the former arise.
These two layers however interlace more than once, and we cannot insulate them without cutting their fibres. The third layer, which is described in most works on anatomy, does not in fact exist.
This muscle has two mucous bursæ. The larger is sometimes united with the capsular ligament of the scapulo-humeral articulation, and is situated on the neck, and at the base of the coracoid process of the scapula. The smaller, which does not always exist, is situated much lower and further forward, between the capsular ligament and the tendon of the muscle.
The subscapularis muscle draws the arm towards the trunk, turns it on its axis from without inward, and depresses it when it is raised. If the arm is fixed it can carry the scapula outward.
rr. TERES MAJOR.
§ 1115. The teres major muscle, Scapulo-humeral , Ch. (AÃ. teres , s. rotundas major, s. déprimons hmnerum rotundas) arises from the lower and triangular part of the outer face of the scapula, and from the posterior lip of the anterior edge, where it usually adheres to the subscapularis and teres minor muscles ; but it soon leaves these two muscles and ascends, always much less obliquely than the teres minor, from which it is separated by the long portion of the biceps, between the latter and the coraco-brachialis, approximates the humerus, and is attached by rather a short, broad, but thin tendon, to the inner rough line, directly behind and a little below the latissimus dorsi.
Its form is the same as that of the teres minor, but it is at least twice as large as that muscle.
We find below and forward, between its tendon, the latissimus dorsi muscle, and the humerus, a small mucous bursa, and beside these, we also find one or more in its anterior tendon where it divides.
This muscle draws the humerus backward, downward, and inward ; when the arm is turned outward, it brings it a little inward.
§ 1116. It is often united with the posterior part of the latissimus dorsi muscle by a large fasciculus which leaves its posterior extremity.
IV. COKACO BHACHIALIS.
§ 1117. The coraco-brachialis muscle, Coraco-humeral , Ch. (M. coraco-brachialis , s. coracoideus , s. perforatus Casserii) is formed like an oblong triangle. United above, rather intimately, and to some extent, to the origin of the short portion of the biceps flexor muscle (§ 1120), it arises from the coracoid process farther forward than the latter. It, is tendinous before, in most of its length, and fleshy behind. In quitting the short portion of the biceps muscle it goes inward, becomes thicker at its central part, but contracts much at its lower end, and is attached, partly fleshy, partly tendinous, to the middle region of the inner face of the humerus.
The musculo-culaneous nerve generally perforates it in its centre. Its lower part often blends with the upper end of the brachialis internus muscle, a curious fact, as it adds a new feature to the analogy between the flexors of the fore-arm and those of the leg. We find one imperfect bursa, and sometimes two, between its upper tendon, that of the short portion of the biceps muscle, and the capsular ligament of the scapulo-humeral articulation.
This muscle approximates the humerus and the scapula to each other, carries the arm to the side of the bodjq and rolls it a little outward, when it is turned inward.
Sometimes, instead of a simple perforation, it presents a real fissure, which is often confined to its lower part, and sometimes exists its whole length, so that the tendons are separated although the musculocutaneous nerve passes constantly between the two portions. This arrangement establishes a striking similarity with the structure of the apes.
3. Muscles of the Arm
§ 1118. The muscles found on the humerus arise partly from this hone, others from the scapula, axrd are attached to the bones of the fore-arm. Theyare the triceps extensor, the biceps flexor, and the brachialis intemus ; the first is situated at the posterior and outer part of the arm ; the other two are placed on its anterior and inner face.
I. TRICEPS EXTENSOR,
§ 1119. The triceps extensor muscle, Scapulo-olecranien , Ch. (JVI. triceps brachii , cubiti , s. brachieus externus , s. posterior) occupies most of the posterior face of the humerus, and extends from the scapula to the olecranon process.
The long or the posterior head ( caput longum, cmconœus longus) arises. by a short, flat, and thick tendon, directly before the anterior insertion of the teres minor muscle, from the upper end of the anterior edge of the scapula, and goes from above downward, gradually increasing in thickness. The tendon descends very low on its inner face. Its lower tendon extends in all its lower half along the inner part of its inner face, and the fleshy fibres are inserted in it obliquely. Its form is elongated.
The large head, or the outer head, ( caput externum, s. magnum, unconcern magnus, s. externus) arises above by a thin extremity which terminates by a convex edge, and presents very short tendinous fibres. This end is attached, directly below the insertion of the teres minor muscle, at the upper part of the posterior face of the humerus. The fleshy fibres come also from all the anterior edge of the bone. This head descends as far as the outer condyle, by a short tendon, which is oblique from above downward, from before backward, and from without inward, unites backward and inward to the lower tendon of the long head. In all its lower portion its inner and posterior pari is covered by the common lower tendon of the brachialis internus muscle Its form is that of an elongated rhomboid, its breadth exceeds its thickness.
The short or internal head arises, directly below the upper extremity of the preceding, from most of the posterior face of the humerus, and descends along the inner edge of the bone to near the inner condyle, rests, by its posterior and inner edge, upon the tendons of the teres major and coraco-brachialis muscles, and also the inner edge of the brachialis internus. Its fibres go obliquely downward and outward ; they are attached to the lower tendon of the long head in all the lower part of the short head.
The common lower tendon of these three heads, which covers them
outwardly at their lower part, is not destitute of fleshy fibres except in
a very small portion of its extent below, and is inserted in the upper
broad edge of the posterior face of the olecranon process of the ulna.
We find a considerable mucous bursa between this tendon and the olecranon process, besides which we sometimes find two smaller ones on each side. We less commonly see another, also smaller, above.
This muscle extends the articulation of the elbow and usually moves the fore-arm ; but it can also move the arm when the fore-arm is fixed. The long head brings the scapula towards the humerus, and draws the latter inward and backward.
II. BICEPS FLEXOR.
§ 1120. The biceps flexor muscle, Scapulo-radial , Ch. ( flexor antibrachii biceps, s. radialis, s. biceps internus ), is a very long muscle, situated on the anterior and the outside of the arm, and extends its whole length. Its two heads are separated above in almost all the muscle, and extend from the scapula, whence they arise, to the upper extremity of the radius.
The internal, posterior, or short head ( caput breve), called also the coraco-brachialis muscle, from one of its attachments, is not only shorter but also thinner than the long head. It arises from the coracoid process by a short, flat, and narrow tendon, which it has in common with the coraco-brachialis muscle, more forward and outward than the latter, proceeds on its outside a little obliquely from within outward, covers below the inner and upper part of the brachialis internus muscle, and lower down becomes a tendon, which is first seen on its external face, on the side corresponding to the long head. This tendon, which unites to that of the last, is attached to the tuberosity of the radius.
Tire long head ( caput longum , s. M. glcno-radialis ) arises by a long, thin, and flat tendon from the centre of the upper part of the edge of the glenoid cavity of the scapula. This tendon is inclosed in a special fold of the capside of the scapulo-humeral articulation, which answers as a mucous sheath, passes upon the head of the humerus, and is situated in the groove between the two tuberosities of this bone, where it is retained by the fibres of the fibrous ligament of the shoulder-joint, and on the anterior extremity of which the mucous sheath ceases. It thus comes to the anterior and outer side of the arm, where it soon continues with its fleshy belly but deeper than the tendon of the short head. This latter descends above, along the anterior and external edge of the triceps extensor muscle ; below, before the central part of yhe brachiahs internus muscle : at its lower extremity it is attached on one side, that is by its internal face, to the tendon of the short head ; on the other to a peculiar tendon contained within it, and which when entirely destitute of fleshy fibres is united with that of the first head, being inserted at the same place with it.
We find a large mucous bursa between the lower tendon, that of the
supinator brevis and the tuberosity of the radius, to which sometimes a
smaller is added, situated on the outer face of the tendon.
The principal use of this muscle is to flex the articulation of the elbow. It also turns the fore-arm backward, contributes to draw it inward when it is extended, and depresses the scapula toward the humerus.
§ 1121. The biceps flexor muscle is one of those muscles most subject to variation, and presents the most singular anomalies.
The least considerable anomaly is where the two heads arise much lower than usual, so that they are only united by the inferior tendon.(l)
A greater anomaly, which is not rare, is when a third head exists, which is usually smaller than the other two and which arises near the centre of the internal face of the humerus, (2) more rarely from only the brachialis internus muscle, (3) although it is often blended with it. Sometimes also it is united with the coraco-brachialis muscle. This anomaly is very remarkable, as it is a repetition of the small head, which properly belongs to the biceps femoris muscle, and because its union with the coraco-brachialis muscle makes the number of the long flexors of the fore-arm equal to those of the long flexors of the leg. At the same time it approximates man to animals ; since in birds the long flexor of the fore-arm presents a second smaller head, which arises from the lower tuberosity of the humerus ; while in apes the brachialis internus muscle extends much higher.
The number of heads of this muscle sometimes increases still more, so that we number five ; but these are not inserted in one common inferior tendon. (4) At the side of the third which is most usually met with we sometimes find a fourth, and along the tendon of the short head a fifth, which unite and are attached to the radius below the usual tendon ; in this case, consequently, there were in fact three flexors, as is always found in birds.
III. BRACHIALIS INTERNUS.
§ 1122. The brachialis internus muscle, Humero-cubital, Ch. (AT. flexor cubitalis ulnaris , s. brachieus intermis ), a broader and thicker muscle, especially at its posterior part, which entirely covers the inferior portion of the internal and anterior faces of the humerus, arises by an external and an internal slip, the former being higher, from the external and internal faces of the humerus above its centre. These two slips surround the lower extremity of the deltoides muscle ; the internal extends to the coraco-brachialis and the external to the upper extremity of the large head of the triceps extensor muscle. Its anterior edge descends along the external edge of the humerus, and the posterior along the internal edge of this bone to the part where it suddenly enlarges.
(1) Weitbrecht, Comment. Petrop., 1731. — Albinus, loc.cit. — Rudolphi, in Gant~er,
6. — We have seen it several times but always on one side.
(2) Albinus, loc. cit., p. 43S, 439. — Mayer, loc. cit.
(3) Kelch, loc. cit., p. 35.
(4) Pietsch, in Roux Journal de Med., vol. xxxi. p. 245.
Its fibres are attached to a strong rounded inferior tendon, which reascends on the anterior face of the muscle almost to its centre. This tendon is inserted in the tuberosity of the ulna.
Between the tendon of the brachialis internus, that of the biceps flexor cubiti, the supinator brevis muscle, and the capsular ligament, we find a mucous bursa, which is not however constant.
This muscle flexes the articulation of the elbow.
§ 1123. We sometimes find at the side of it, but more forward and outward, a second brachialis internus muscle, which is smaller and which is an exact repetition of it as respects its attachments, the inferior tendon of which is inserted deeper than that of the other, and which even presents a rudiment of the preceding muscle, which we said belonged to birds. The first degree of this anomaly is the separation of the posterior from the anterior part of the muscle, which not unfrequently occurs. This division of the brachialis internus muscle into two parts is also worthy of remark, as it assimilates this muscle to the flexors of the leg. Its abnormal union with the biceps flexor by a muscular slip (§ 1121) is on the contrary the first index of the formation of a third head to the latter (§ 1121).
The anomalies of the brachialis internus, the biceps flexor, and the coraco-brachialis muscles (§ 1116), considered collectively, seem to be so many efforts by which nature endeavors to establish a perfect resemblance between the upper and lower extremities. They are generally found singly ; but if we suppose them united, we have an arrangement perfectly similar to that of the lower extremities.
The coraco-brachialis and brachialis internus muscles, divided into two portions and often united with each other, evidently represent the semimembranosus and the semitendinosus muscles. The muscular band which goes from the brachialis internus to the lower part of the biceps flexor muscle, united with the unusually deep division of the latter, may be considered as tending to insulate the two heads and to form a second flexor of the ulna, even as the tibia is flexed by two distinct muscles.
4. Muscles of the Fore-Arm
§ 1124. The muscular mass of the fore-arm is formed of those muscles which move the bones upon each other or on the humerus, by the muscles which act on the carpus, and by the long muscles of the fingers.
The motions of the bones of the fore-arm on each other, or pronation and supination, are performed by four muscles, the supinator longus and the supinator brevis, the pronator teres and the pronator quadratus, all of which except the first are situated deeper than the other muscles of the fore-arm.
The two bones of the fore-arm are moved on the humerus by one muscle, the anconeus.
Five muscles move the carpus ; the extensor carpi radialis longus and the extensor carpi radialis brevis extend it ; it is flexed by the flexor carpi ulnaris and the flexor carpi radialis muscles ; the extensor carpi ulnaris draws it backward.
The fingers are extended by the extensor digitorum communis, the extensor pollicis longus and brevis, the extensor indicis proprius, and the extensor minimi digit i proprius ; they are flexed by the flexor sublimis, the flexor profundus, and the flexor pollicis longus.
These different muscles succeed each other in the following order, when we commence their description at the radial edge and follow the external face of the fore-arm to the ulnar edge and return from this to the radial edge along the internal face of the arm.
I. MUSCLES OF THE INTERNAL FACE OF THE FORE-ARM.
I. SUPINATOR LONGUS.
§ 1 1 25. The supinator longus muscle, Humero-sus-radial , Ch.,is a long muscle, which arises by short tendinous fibres from the inferior part of the anterior edge of the humerus, where it unites with the large head of the triceps extensor muscle. It goes downward and passes on the inferior and external part of the brachialis internus, which it covers, and reaches the fore-arm along and before the inferior extremity of this muscle ; it goes on the radial edge of the fore-arm and is changed high up into a long and thin tendon, which covers above only the internal face, and is finally attached to the anterior face of the internal edge of the radius, a short distance above its inferior face. It turns the radius backward and inward, consequently carries the hand to the state of supination, and flexes the fore-arm.
II. EXTENSOR CARPI RADIALIS LONGUS.
§ 1126. The extensor carpi radialis longus muscle, Humero-susmetacarpien , Ch., resembles the preceding and appears at first view to be a part of it. It arises from the lowest part of the outer edge of the humerus, descends to the outer condyle, passes on the outer part of the articular edge of the humerus, and on the head of the radius ; in its course it becomes first thicker, afterward narrower, and terminates at the same place as the preceding in a tendon, at first rather broad, flattened, and loose to a much greater distance, which descends in the same direction along the radius and enters below into the anterior groove of the outer face of the lower extremity of the radius under the posterior ligament of the carpus, thus arrives at the carpus and is attached to the anterior part of the posterior face of the base of the second metacarpal bone.
The lower tendon is surrounded with a mucous sheath where it passes over the lower extremity of the radius. We also find a small bursa at its insertion in the root of the second metacarpal bone.
This muscle extends the hand and draws it a little toward the radial side of the fore-arm ; it also serves to execute the motion of pronation toa certain extent and flexes the articulation of the elbow.
§ 1127. Sometimes a smaller and feebler muscle is detached from its lower edge, which succeeds the extensor carpi radialis brevis muscle and is attached a little above it to the root of the third metacarpal bone.(l)
III. EXTENSOR CARPI RADIALIS BREVIS.
§1128. The extensor carpi radialis brevis muscle, Epicondylo-susmétacarpien , Ch., is very similar to the preceding, but is smaller. Its upper tendon, which is very strong, exists nearly the whole length of its posterior face. It arises from the anterior face of the outer condyle of the humerus, and is attached, below the middle of the fore-arm, by an elongated, flat, but narrow tendon, the upper part of which covers the lower part of the outside of the muscle. This tendon is inserted in the outer face of the base of the third metacarpal bone, and slightly also in that of the second. There is a small bursa between it and the third metacarpal bone.
This muscle acts in the same manner as the preceding.
§ 1129. It is sometimes entirely deficient, (2) as in several mammalia, where we never find but one extensor radialis muscle : the first degree of this formation is the complete union of the second radialis muscle, of which several instances are known. Sometimes its tendon divides into two slips, which are attached to the third metacarpal bone only, or one is inserted into this bone, and the other into the next ; even as in the mammalia, which have only one radialis muscle, the tendon divides into two slips.
Besides the bursæ already mentioned, the tendons of the two muscles are surrounded by two common sheaths, the upper of which is situated above the lower end of the radius, while the lower is placed at a short distance from it on this extremity, and on the upper range of the carpal bones.
IV. EXTENSOR DIGITOnUM COMMUNIS.
§ 1130. The extensor digitorum communis muscle, Epicondylo-sttsphalangettien commun , Ch., commences by a strong tendon, which extends on the upper part of the external face of its belly. It arises from the lower and back part of the outer condyle of the humerus, directly under and behind the radialis externus brevis muscle, with which it is intimately connected for several inches. Near the centre of the fore-arm it separates into three bellies, the posterior of which also divides a little farther in two others, so that the whole number of these bellies is four ; these are inserted into as many elongated and flat tendons, of which the second is usually the strongest, the third smaller than the first, and the fourth is the weakest.
(1) Albinus, Inc. cit., p. 448.
(2) J. G. Salzmann, Diss. sist. rdurium pedis musculorum defectum, Strasburg', 1734, p. 11.
All these tendons pass under the posterior ligament of the carpus, between it and the outer face of the lower end of the radius. They become broader and thinner on the back of the hand, partially separate, especially near the anterior end of the metacarpus, and are again united by strong oblique intermediate tendons of various breadths. They go to the second, third, fourth and fifth fingers, and contract on the articulation of the metacarpus with the phalanges ; but in this place they give off on each side fibres, which go downward ; farther on they again enlarge, and are blended on each side with the tendons of tho interosseous muscles. On the first joint of the phalanges they divide into a central and two lateral portions, which are much longer ; the central tendon, having strengthened the dorsal face of the capsular ligament, is attached to the upper edge of the base of the second phalanx ; the other two are united forward, and are inserted in the upper part of the back of the third phalanx.
At the lower end of the fore-arm, of the carpus and metacarpus, the tendons of this muscle have a mucous sheath, which is single above, but divides on the carpus into three branches, each of which goes with its tendon to the base of the first phalanx.
This muscle extends the second, third, fourth, and usually the fifth finger also.
§ 1131. Sometimes its three bellies are separated high up, and even at their origin. ( 1 ) Sometimes it divides into four tendons ; the fourth goes to the little finger, and unites to its proper extensor. This fourth tendon sometimes divides on the back of the hand into two parts ; the outer joins the tendon of the extensor minimi digiti proprius muscle, and the inner again divides into two portions, one of which unites to the tendon of the fourth finger, and the other to that of the fifth. (2) In some subjects the third and fourth tendons go to the third finger. In this case the muscle itself often divides into two bellies, each of which has two tendons. (3)
These divisions of the fleshy part of the muscle are curious, being similar in one respect to the extensors of the toes and also to the flexors of the fingers, which are both double.
(1) Albinus, loc. cit., p. 452. — Brugnone, loc. cit., p. 167.
(2) Albinus, loc. cit.
(3) Brugnone, loc. cit.
V. EXTENSOR MINIMI DIGITI PROPRIUS.
§ 1132. The extensor minimi digiti proprius muscle, Epicoudytosus-phalangetlien du petit doigt , Ch., is slender, elongated, and thin. It arises bj two tendinous heads from the outer part of the head of the radius, from the part of the capsular ligament surrounding this head, and from the upper end of the anterior edge of the ulna. It descends behind the preceding, with which it is closely united for some distance, and near the lower end of the fore-arm becomes a thin tendon, which passes below the posterior ligament of the carpus in a special groove, enlarges along the metacarpal bone of the fifth finger, unites inward with the fourth tendon of the preceding muscle, and is attached to the upper face of the head of the third phalanx of the little finger.
Its tendon is surrounded from the lower part of the fore-arm to the centre of the fifth metacarpal bone by a sheath, which is single above, but below divides like the tendon into two parts.
This muscle extends the little finger.
§ 1133. It is sometimes deficient, (1) and then it is generally replaced by a tendon of the extensor digitorum communis muscle. In other cases, on the contrary, its tendon divides into two slips, one of which goes to the fourth finger, an arrangement worthy of remark because of its analogy with several mammalia.
VI. EXTENSOR CARPI ULNARIS.
§ 1134. The extensor carpi ulnaris muscle, Cubito-sus-metacarpien, Ch. (M. ulnaris externus , s. extensor manus ulnaris ), arises by two tendinous slips, of which the smaller and shorter is situated at the side of the extensor digitorum communis, and comes from the posterior and lower part of the external condyle of the humerus, and the longer arises from the upper part of the anterior face of the tubercle of the ulna. These two. slips soon unite in a considerable belly. The latter is tendinous at its inner and outer faces, and adheres in a considerable extent to the extensor proprius minimi digiti muscle, descends along the outer face of the ulna, from which it receives some fibres, and becomes, near the lower third of the fore-arm, a strong tendon, which, passing across a particular portion of the dorsal ligament of the carpus, comes on the back of the hand, where it is attached to the tubercle of the metacarpal bone of the fifth finger. There is but one mucous bursa between its upper extremity and the head of the radius.
This muscle extends the hand and draws it backward toward the posterior edge of the fore -arm.
§ 1135. A tendon of greater or less extent is often detached to go to the fifth finger, and at the base of the first phalanx unites with that of its proper extensor.
(1) Brugnone, p. 167. — Wc have known two instances where it was deficient.
VII. ANCONÅ’US.
§ 1136. The anconœus muscle, Epicondylo-cubiial, Ch. (J\I. anconœus , s. anconœus quartus), is a triangular muscle and mostly covered by the upper extremity of the preceding ; it arises by a short and strong tendon from the i nner part of the outer condyle of the humerus, descends toward the ulna, and is attached by a broad fleshy surface to the upper part of the anterior face of this bone. Its upper straight edge usually blends with the outer belly of the triceps extensor muscle.
This muscle extends the fore-arm, also turns the radius backward, so that it assists in supination.
VIII. SUPINATOR BREVIS.
§ 1137 . The supinator brevis muscle, Epicondylo-radia! , Ch., is triangular ; its base looks upward, and its apex downward. It arises from the upper part of the anterior face of the ulna, and is tendinous outwardly and fleshy inwardly. Its upper fibres are transverse and the lower oblique. It goes downward and forward, turns on the upper part of the radius, and is attached by a broad fleshy edge to the anterior part of the capsule of the ulna, and also to the upper part of the anterior and inner faces of the radius as far as its posterior edge. It turns the hand and the radius on their axes backward and outward.
§ 1138. The upper part of this muscle often separates from the lower sooner than usual, and differs from it in the direction of its fibres, is separated from it by the radial nerve, and is attached to the radius without being connected with it. This anomaly leads to that in which two small supinator muscles exist ; the upper extending from the outer condyle of the- humerus to the anterior edge of the upper end of the radius, while the internal goes from the head of the radius to its centre. (1) Probably the second variety may be considered as an index of the formation peculiar to apes, in which three supinators exist. (2)
IX. ABDUCTOR POLLICIS LONGUS.
§ 1139 . The abductor pollicis longus muscle, Cubito-sus-métacarpien du pouce , Ch., is a considerable muscle inserted, by very short tendinous fibres, directly below the anconeus and the supinator brevis, to the second fifth of the anterior edge of the ulna, to the outer face of the interosseous ligament, and to the central part of the outer face of the radius. It descends along the last, passes below on the anterior face of the radius, and there becomes a strong tendon, which passes through a particular division of the dorsal ligament of the carpus. This tendon generally divides into two or three slips : the strongest, which is also the most anterior, is attached to the radial edge of the base of the first metacarpal bone ; the other two blend with the posterior extremity of the antagonist muscle of the thumb.
(1) Sandifort, Hist. muse. p. 93. — Brugnone, loc.cit. p. 163.
(2) We have found at least in the Simia apella two long- supinators, situated at the side of each other.
The tendon near its upper extremity is surrounded by a large, oblong,
and rounded mucous sheath.
This muscle separates the thumb from the fingers, and moves it toward the radius.
§ 1140. It is often more or less divided into two bellies, each of which terminates by a tendon, and the lower is usually larger than the upper. The tendons of these two bellies are often divided, and sometimes unite ; sometimes they are attached to the first bone of the metacarpus and to the trapezium.(l)
We more rarely find a digastric abductor of the thumb, which arises from the outer condyle of the humerus, and is inserted into the base of the first phalanx of the thumb.
X. EXTENSOR POLLICIS BREVIS.
§ 1141. The extensor pollicis brevis muscle, Cubito-sus-phalangien du pouce , Ch., is a very small muscle, situated below the preceding, and adheres intimately to its inferior edge. It arises from the outer face of the interosseous ligament and from the radius, and becomes a very thin tendon, which passes through the dorsal ligament of the carpus in the same groove with the abductor pollicis longus, then goes on the back of its metacarpal bone, becomes broader, and is attached to the centre of the upper edge of the base of its fjrst phalanx.
This muscle extends the thumb, and at the same time removes it from the other fingers.
§ 1 142. A small tendon sometimes arises from the anterior extremity of its tendon, which blends with that of the next muscle.
Sometimes this muscle does not exist as a distinct muscle, and forms only the lower part of the abductor pollicis longus muscle.
XI. EXTENSOR POLLICIS LONGUS.
§ 1143. The extensor pollicis longus muscle, Cubito-sus-phalangettien du pouce , Ch. (J\I. extensor pollicis major s. longus ), is much stronger than the preceding, and covers its upper part ; it arises, a little below the abductor magnus, and directly below its upper extremity, above from the outer face and below from the anterior edge of the ulna, and from the adjacent part of the external face of the interosseous ligament. It soon becomes a long tendon, which passes through the second groove of the dorsal ligament of the carpus, goes forward at the side of the preceding, but much more inwardly, partially covers it, and is attached to the base of the second phalanx of the thumb, in the same manner as the tendon of the extensor digitorum communis is ; but it does not divide.
(1) Fleischmann, in the Erlanger Abhand ., vol. i. p. 28.
Its tendon has two mucous sheaths : the upper and larger is situated at the lower part of the fore-arm, and extends to the carpus ; the
inferior is smaller, and is placed on the carpus and on the base of the
first metacarpal bone.
It extends the thumb, and brings it a little towards the other fingers.
§ 1144. Sometimes it is completely double.
XII. EXTENSOR INDICIS PROPRIUS.
§ 1145. The extensor proprius indicis muscle, Cubilo-sus-phalangettien de l'index , Ch. (JVf. indicator , s. indie atorius, s. indicis extensor , s. abductor ), is nearly as large as the preceding. It arises directly below it by two slips from the third quarter of the anterior face of the ulna, and near the lower part of the fore-arm becomes a strong tendon, which, covered by that of the extensor digitorum communis, passes with it through the third division of the dorsal ligament of the carpus, below the tendinous band which goes from the latter muscle to the indicator finger ; it proceeds more inwardly than this band, and is attached to the base of the first phalanx of the finger, blending with it.
It extends the indicator finger, and approximates it a little towards the third.
§ 1146. Sometimes it is digastric, and interrupted in its course by a long tendon.(l)
This muscle presents several anomalies which are exceedingly interesting : they consist in its more or less perfect multiplication and in the formation of the extensor pollicis tertii proprius.
The lowest degree of this anomaly is the division of its portion into two slips both of which go to the second finger, (2) or the division of its belly into two parts, the tendons of which unite before arriving at this finger, (3) or finally the existence of two bellies of the usual size, which are entirely distinct., and of which one arises from the radius. (4)
The most complete anomaly is when one of the slips of the tendon does not go to the indicator, but to the middle finger. (5)
Sometimes a small and perfectly distinct muscle arises from the lower part of the outer face of the radius and from the dorsal ligament of the carpus, and is attached to the first phalanx of the indicator. (6) This variety is only a more perfect development of the case in which the muscle arises by two heads.
(1) Rosenmüller, loc. cit., p. 6.
(2) We have seen it several times.
(3) Albinus, p. 45S. — Heymann, p. 13.
(4) Gantzer, p. 14.
(5) Albinus, p. 468. — Peitsch, Syllogc obs. anat.
(6) Albinus, Ann, acad.. vol. iv. ch. vi.— Hevmann, p. 12.
Next comes the anomaly where we find a proper extensor of the middle finger ; this muscle is always smaller than the extensor indicis proprius, and arises more or less below and under it. This formation varies the least possible from the normal state when the new muscle comes from the ulna;(l) but sometimes it arises from the radius(2) or from the dorsal ligament of the carpus. (3)
The greatest anomaly is where we find, beside the extensor indicia proprius, an extensor for the middle finger, which divides into two tendons, one of which is attached to the metacarpal bone of the index finger, and the other to that of the middle finger.
Finally, we have seen in one case a small tendon, which extended from this proper extensor of the middle finger to the base of the first phalanx of the index finger.
All these anomalies are curious in two respects : 1st, as a repetition of the normal formation of the lower extremities, since they represent the extensor communis digitorum brevis, and that more perfectly as the supernumerary muscles arise lower ; 2d, as analogous with animals ; for in many apes the tendon of the extensor indicis proprius furnishes a slip to the middle finger, and in others, for instance in the simia apella, we find a proper extensor of the index finger. (4)
II. MUSCLES OF THE INTERNAL FACE OF THE FORE-ARM.
I. palmaris Longus and brevis and the palmar aponeurosis.
§ 1147. The palmaris longus muscle, Epitrocldo-palmaire , Ch., is a thin oblong muscle, which arises, directly below the preceding and farther back than it, from the upper part of the anterior face of the inner condyle of the humerus. It goes directly forward and downward, and becomes in the middle of the fore-arm a broad and thin tendon, which is very near the skin. This tendon however is covered by the anti-brachial aponeurosis in most of its length, and passes over this aponeurosis only at its lower part. At its lower end, it divides into two fasciculi : the anterior, which is shorter, and which is attached to the posterior end of the abductor pollicis ; and the posterior, which is much larger, and is called the palmar aponeurosis ( aponeurosis palmaris). This aponeurosis is thinner than the tendon, but much broader and triangular. It gradually enlarges from behind forward, so that it corresponds by its anterior edge to the four fingers. It however becomes thin, and its fibres occasionally have intervals between them.
It is composed essentially of longitudinal fibres, like the tendon of which it is the expansion. Its anterior edge is however formed of transverse fibres, which are arranged over the preceding.
It covers most of the muscles of the palm of the hand, except those of the thumb and the little finger.
(1) We have seen it several times.
(2) We have seen it once.
(3) Brugrione, loc. cit., p. 168.
(4) Meckel, Bey trage zur vergleiehéndeji anatomie, vol. ii. p. 11.
The palmaria brevis muscle, which is composed of transverse fibres,
is attached to its internal edge at its upper part. This muscle, the
internal edge of which comes from the skin, serves to tense the aponeurosis outwardly.
§ 1148. The palmaris longus muscle is often deficient ; sometimes it is replaced by a tendon of the flexor digitorum sublimis.(l ) In other cases, on the contrary, it is unusually developed in fact thinner, but very broad, and descends almost into the palm of the hand. (2) This rudiment of a peculiar muscle, which sometimes extends from the coronoid process of the ulna to the palmar ligament of the carpus, is worthy of remark, especially as it forms an analogy with apes. (3)
II. RADIALIS INTERNUS.
§ 1149. The radialis internus muscle, Epitrochlo-metacarpien , Ch. (JVT. radial is internus, s. flexor manus radialis), is much larger than the preceding, and is blended above with it, and on both sides with the pronator-teres and the flexor communis digitorum sublimis ; it comes from the anterior face of the inner condyle of the humerus, and sometimes also by a small head from the radius. It is partly covered by the preceding and goes downward and a little forward, and near the middle of the fore-arm becomes a broad tendon. This tendon passes under the palmar ligament of the carpus in a special canal, formed by the palmar ligament, and by the os trapezium ; it is harder and thicker in this place than in other parts. After leaving this canal it becomes thinner but broader, and is attached partly to the os trapezium, but more particularly to the inner face of the second metacarpal bone.
We find a mucous bursa between the lower end of the tendon, the os trapezium, and the proper palmar ligament.
This muscle flexes the hand and carries it a little forward.
III. PRONATOR TERES.
§ 1150. The pronator teres muscle, Epitrochlo-radial, Ch., a shorter but stronger muscle, arises by very short tendinous fibres from the upper edge and the upper part of the anterior face of the inner condyle of the humerus. It swells a little below its origin, goes obliquely downward and forward, and is covered at its lower part and at its upper edge by a strong tendinous expansion, and is attached by means of this, below the supinator brevis, and before the abductor pollrcis longus, to the anterior face and outer edge of the radius, a little above its centre.
It turns the radius and also the hand inward, forward, and downward.
(1) Rosenmüller p. 6.
(2) Albinas, p. 474.
(3) Perrault, Mem. in Valentin i Theatr. zoot. p. 151. — Virq. ü’Azyr., Eveycl, meth., sect.anat., vol. ii. p. 25, 257.
§ 1151. It is sometimes double. In this case the supernumerary muscle extends from the posterior edge of the ulna to the posterior edge of the normal muscle, which is an analogy with apes.
IV. FLEXOR ULNARIS.
§ 1152. The flexor ulnaris muscle, Cubito-carpien , Ch. (JVT. ulnaris internus, s. flexor ulnaris), arises by two rather short heads, of which the upper comes from the lower part of the inner face of the inner condyle of the humerus, and the posterior or the inferior from the inner face of the olecranon process of the ulna. It descends along the ulna, from which it is always separated by the flexor digitorum communis, and becomes a strong tendon at the lower end of the fore-arm which is attached to the pisiform bone ; we find a very loose mucous bursa between it and this bone.
It flexes the hand and inclines it toward the ulna.
V. FLEXOR DIGITORUM COMMUNIS SUBLIMIS.
§ 1153. The flexor digitorum communis sublimis muscle, Epilrochlophalanginien commun , Ch. (JM. flexor digitorum communis sublimis , s. perforatus ), arises below the four preceding, by a much larger head, from the lower part of the anterior face of the inner condyle of the humerus, from the inner part of the capsular ligament of the elbow joint, and from the inner face of the coronoid process of the ulna ; it also arises by a small slip from the inner face of the radius at the lower end of the supinator brevis muscle. Tong before this slip has joined the upper head, it divides into three bellies, of which the internal and posterior divide still lower into two others. Each of these bellies becomes a tendon, which all pass under the special palmar ligament of the carpus to arrive at the palm of the hand.
Nearly opposite the centre of the first phalanx each tendon divides into two slips which unite farther on the second phalanx, so that their inner fibres interlace and again separate below this point to attach themselves behind the middle of the second phalanx to its radial and ulnar edges.
These tendons are surrounded by a common sheath, near the lower extremity of the fore-arm, which, when arrived at the carpus, divides into several sacs, each of which goes with one of them to the base of the first phalanx. This muscle flexes the second phalanx of the fingers.
§ 1154. One of the tendons, particularly that of the little finger, is sometimes deficient ; it is then replaced by one of the tendons of the flexor profundus muscle ; sometimes a belly of this muscle, especially that which belongs to the index finger, is entirely separated from the others, and divided besides into two fleshy portions by a long central tendon. As the anomaly is seen more commonly in the belly of the indicator finger, it is worthy of remark, from its analogy with the outer face of the fore-arm, since it represents the proper extensor of the index finger, and more, as the latter is also digastric in some subjects.
VI. FLEXOR DIGITORUM PROFUNDUS.
§ 1155. The flexor digitorum profundus muscle, Cubit n-phalangettien commun, Ch. (JVJ. flexor digitorum communis profundus, s. suadus perforons), is stronger than the preceding, which covers it anteriorly, and arises from the upper two-thirds of the inner and posterior faces of the ulna, so as to envelop this bone almost entirely, and divides, but much deeper than the flexor sublimis, into four bellies, which become as many tendons. These tendons are retained together by numerous intermediate filaments and by folds of the mucous sheaths, and pass under the palmar ligament of the carpus, with those of the preceding, and go to the same fingers. In this place we see a fissure along the upper and lower faces. They pass through the sheath of the flexor sublimis, afterwards become broader and thinner, and are attached to the base of the third phalanx.
This muscle flexes the third phalanx of the fingers.
§ 1156. Sometimes a muscle proceeds between the flexor sublimis and the flexor profundus, and extends from the inner condyle of the humerus to the latter ;(1) and again, a muscular fasciculus arises from the flexor pollicis longus as high as the wrist, which is attached by a tendinous expansion to that tendon of the flexor profundus which goes to the index finger.(2)
VII. LIGAMENTS OF THE FLEXORS OF THE FINGERS.
§ 1157. The tendons of the flexor profundus and sublimis are surrounded in two places by fibrous ligaments and mucous sheaths. 1
§ 1158. The upper fibrous ligaments are the common palmar ligament and proper palmar ligament of the carpus.
Below them we find the upper mucous sheath, an elongated sac, which surrounds all the tendons of the two flexors, commences about an inch and a half above the radio-carpal articulation, and extends to the centre of the carpus. Its outer layer is attached to the palmar ligaments of the bones of the carpus, and to the interossei muscles. Numerous folds arise from all the internal face of this outer layer which go inward, surround the tendons of the two flexors, and unite them but very loosely.
§ 1159. The second place, where the common flexors are surrounded with similar ligaments, is that portion which corresponds to the lower face of the fingers.
§ 1160. The lower fibrous ligaments are situated outwardly, and form for the mucous sheath an envelop, which is divided on account of the motion of the fingers,
(1) Gantzer, p. 13.
(2) Gantzer, ibid.
The strongest portion is termed the ligamentous sheaths ( Lig . vaginalia). These sheaths are formed almost entirely of transverse fibres ; in part, however, especially on the surface, of oblique fibres which cross the preceding. They are strongly extended, like a bridge, from the radial to the ulnar edge of the first and second phalanges. That of the indicator finger is much stronger than the others in every respect.
The feeblest which stand more distinct, extend in the same manner over the metacarpo-phalangoean and the second phalangoean articulations. Their size diminishes much from the first to the third articulation. They are called the ligamentous rings of the articulations ( annuli juncturarum ligament osi).
Analogous fasciculi are found between the preceding and the ligamentous sheaths ; these are the oblique or crucial rings of the first and second •phalanges ( annuli obliqui , s. cruciati phalangis primes et secundcE ).
§ 1161. The inner faces of these fibrous ligaments are covered with elongated mucous sheaths, which begin some lines behind the metarcarpo-phalangœan articulation, are attached in this place to the flexor sublimis and profundus of each finger, and extend to the centre of the terminating phalanx. Their upper part is inserted in the upper part of the palmar face of the phalanges. The tendons of the two flexors are mostly loose in these mucous sheaths, of which each finger possesses a separate one ; however, from the dorsal face of the sheaths, that which covers the palmar face of the fingers, arise several broader and narrower irregular folds, the largest of which contains more or less fat ; these proceed from before backward, are very thin from one side to the other, and are attached to the tendons of the flexor sublimis and profundus. The upper are usually very thin and rounded, and are attached to the radial slip of the flexor sublimis. They are generally deficient in one or several fingers.
The succeeding which are larger are also more constant ; they arise near the second phalangcean articulation, and are usually attached to the tendon of the flexor sublimis, where its two slips unite. Usually we find also within or on their sides other prolongations, which go to the tendons of the flexor profundus.
A third prolongation generally arises from the base of the third phalanx which is attached directly to the two anterior slips of the flexor sublimis, unites them, goes from this point to the anterior extremity of the flexor profundus which covers the third articulation, and is there attached in all its extent.
Other single or divided prolongations extend also in many parts between the tendons of the two flexors in their course along the fingers.
These are the short and long accessory or vascular ligaments of the flexors (vincula tendinum sublimis el profundi accessoria , s. vasculosa brevia et longa).
VIII. FLEXOB POLLICIS LONGUE.
§ 1162. Th e flexor proprius pollicis longus muscle, Radio-phalangettien du pouce , Ch., is much feebler and shorter than the preceding, with the second belly of which its central part usually adheres more or less intimately. It arises by a small distinct slip from the tubercle of the ulna, but in most of its length it arises by fleshy fibres from the lower two-thirds of the inner face, and the anterior edge of the radius. The strong tendon which terminates it passes under the palmar ligament with those of the two preceding muscles, and goes between the abductor and flexor pollicis brevis on the internal face of this finger, and is attached not far from its inferior edge to the second phalanx. This tendon is surrounded by a special mucous sheath from the lower extremity of the fore-arm to the centre of the first phalanx.
It flexes the second phalanx of the thumb.
We sometimes find a second head which comes from the inner condyle of the humerus, and which is only a greater development of its upper slip.
IXL .PRONATOR Q.UADR ATUS.
§ 1163. The pronator quadratus muscle, Cubito-radial , Ch. (JV I. pronator quadratus, s. inferior), is an almost equilateral quadrilateral muscle, being rather more long than broad, which occupies the lowest part of the inner face of the fore-arm, where it is covered by the tendons of all the long muscles. Its fibres are oblique and extend from the posterior edge and from the inner face of the ulna to the inner face and anterior edge of the radius.
This muscle rotates the radius, and the hand with it, on its axis from behind forward and from without inw T ard.
§ 1164. It is sometimes deficient, (1) as in several mammalia.
Again, it is sometimes divided into two bellies which are entirely separated, the fibres of which proceed in opposite directions and cross. (2)
5. Muscles of the Hand
§ 1 165. The musclesof the hand(3) arisefrom the tendonsof the flexor profundus, from the carpus, and from the metacarpus, and are attached to the metacarpal bones and also to the phalanges. They are principally designed to approximate and separate the fingers and serve less to flex them. Hence they are divided into abductors, adductors, and flexors. The adductors and abductors which are attached to the two external fingers, the thumb, and the little finger, fulfill only the one or the other of these two functions, while those which move the other three fingers are both adductors and abductors ; because, in approxiting a finger toward that on one side, they necessarily separate it from that of the other side.
(1) We know of one instance.
(2) We have once seen this.
(3) Albinus, leones musculorum inanus iv., ad ealeem hist, muscul., Leyden, 1734,
The abductor and adductor muscles of the fingers, except the thumb, are] called the interossei muscles, from their situation ; the flexors of the second and third and also one of the little finger are called the lumbricales , from their form.
I. LUMBRICALES.
§ 1166. The four lumbricales muscles, Palmi-phalangien, Ch., are long, rounded muscles, which arise fleshy from the lower face and the radial edge of the tendons of the flexor digitorum profundus toward the upper end of the metacarpus. They proceed at the side above and below these tendons and arrive at the fingers, where they become thin tendons, which are reflected on the radial face of the first phalanx, enlarge, and blend with the anterior edge of the tendon of the extensor muscle.
They flex the first phalanx.
§ 1167. We often find one or more of these muscles more or less completely double, and then the supernumerary head or the whole muscle is inserted in the ulnar side of the adjacent finger.
II. INTEROSSEI.
§ 1168. The interossei muscles, Metacarpo-phalangiens latéraux sus-pahnaire and the métacarpo-phalangiens Intermix, Ch., are situated between the metacarpal bones. Their anterior tendons are attached partly to the lateral faces of the posterior heads of the first phalanges, partly also to the extensors of the fingers. They are divided into two classes, the external (JVT. interossei externi , s. bicipites), and the internal (M. interossei interni , s. simplices.)
I. INTEROSSEI EXTEBNI.
§ 1169. The common characters of the external interossei muscles are : 1st. They appear on the dorsal and palniar faces of the hand. 2d. They arise from the corresponding faces of two metacarpal bones by two heads, which is inserted in a common tendon.
We number four, which are attached to the index, middle, and little fingers.
The first, which is the strongest, is situated between the thumb and the index finger. It differs from the others, not only in volume but also in the complete separation of its two heads.
The anterior and stronger head arises from the upper larger part of the ulnar face of the metacarpal bone of the thumb. The posterior, which is smaller, arises from almost all the radial face of the second metacarpal bone. These two heads unite below in a common tendon, which is attached partly to the radial face of the base of the first phalanx of the index finger, and partly blends with the tendon sent by the common extensor of the same finger.
The great distance between the two heads has led some anatomists to consider them as two distinct muscles : they have termed the anterior head the adductor indicts and the posterior the first internal interosseous muscle.
It draws the second finger toward the thumb.
The other external interosseous muscles are much smaller ; their heads unite much higher even in the centre of their course.
The second arises by a smaller anterior and deeper head from the ulnar side of the second, and by a larger posterior looser head from the radial side of the third metacarpal bone. It is also attached to the radial side of the middle finger.
This muscle brings the middle finger toward the index finger.
The third, situated in the space between the third and fourth metacarpal bones, is inserted in the ulnar side of the middle finger.
It brings the middle finger toward the fourth.
The fourth is placed between the fourth and fifth metacarpal bones, and is inserted in the ulnar side of the fourth finger.
It brings the ring finger to the fifth,
II. INTEBOSSEI INTERNS.
§ 1170. The interossei intemi muscles are three in number, when we do not consider the posterior head of the first external interosseous muscle as the first internal interosseous muscle. They are attached to the second, fourth, and fifth fingers. They arise by a single head from the lateral face of the metacarpal bone of the finger to which they are attached, and are very distinct in the palm of the hand.
The first arises from the ulnar face of the second metacarpal bone, is inserted in the ulnar side of the base of the first phalanx of the indicator finger, and blends in the same place with the tendon sent by the common extensor to this finger. It separates the index finger from the thumb and draws it toward the middle finger.
The second comes from the radial side of the fourth metacarpal bone.
The third arises from the radial side of the fifth metacarpal bone.
The second is attached to the first phalanx of the fourth finger, and the third to the first phalanx of the fifth finger.
Both draw the fingers to which they are attached from the side of the thumb or from the radial edge of the hand, and consequently inward.
The index finger has then an external and an internal interosseous
muscle ; the middle finger has two external interosseous muscles ; the
fourth finger an external and an internal, and finally the fifth finger
an internal interosseous muscle.
§1171. The interosseous muscles rarely present anomalies. We have however found the second external interosseous muscle attached to the ulnar side of the index finger, and the first internal interosseous muscle attached not to this finger but to the radial side of the third — a variety the more interesting in the history of the inversion of the organs because it presents an exact repetition of the normal formation of the foot, and because the hand in which we found it presented also an adductor of the thumb, formed likewise in the same manner as that of the great toe.
III. MUSCLES OF THE THUMB.
§ 1172. The metacarpal bone of the thumb is surrounded by a considerable muscular mass, called the ball of the thumb (thenar), formed of four muscles, the abductor pollicis brevis, the opponens pollicis, the flexor pollicis brevis, and the adductor pollicis.
I. ABDUCTOR POLLICIS BREVIS.
§ 1173. The abductor pollicis brevis muscle, Carpo-sus-phalangien du pouce, Ch., the most superficial of the four muscles, arises from the anterior part of the inner face of the ligament of the carpus and of the os trapezium. It is generally blended by a short intermediate tendon with the tendon of the abductor longus (§1139), and extending forward along the radial edge of the metacarpal bone of the thumb, it is attached by a short tendon to the outer face of the posterior head of its first phalanx. It also usually blends more anteriorly with the tendon of the flexor pollicis brevis muscle.
It separates the thumb from the index finger and extends it a little.
II. OPPONENS POLLICIS.
§ 1174. The opponens pollicis muscle, Carpo-metacarpien du pouce, Ch., is smaller than the preceding, which it partly covers, and its form is rhomboidal. It arises below it by a broad edge and by very broad tendinous fibres from the anterior part of the inner face of the palmar ligament and from the os trapezium, then descends to the metacarpal bone of the thumb, and is attached by a short tendon to all the anterior part of its radial edge.
It draws the thumb inward and turns it on its axis ; so that it opposes its palmar face to that of the other fingers.
III. FLEXOR POLLICIS BREVIS.
§ 1175. The flexor pollicis brevis muscle, Carpo-phalangien du pouce, Ch. {J\l. flexor pollicis brevis , s. mesothenar , s. antithenar ), is stronger than the two preceding. Its upper extremity, which is very much divided, arises first below and inward from the palmar ligament and the os trapezium, on the other side from the palmar face of the os trapezoides, from the os magnum, and the os pyramidale. It partly covers the preceding and is attached to the outer sesamoid bone of the thumb.
It flexes the first phalanx of the thumb.
§ 1176. The largest head, which comes from the palmar ligament, is sometimes entirely separated from the other, which is smaller and situated lower ; so that this muscle is in fact double. On the other hand, it often happens that the small head is entirely blended with the adductor pollicis muscle.
IV. ADDUCTOR POLLICIS.
§ 1177. The adductor pollicis muscle, JVIetacarpo-phalangien du pouce , Ch. (JVT. mesothenar , s. hypothenar ), is the strongest and the deepest of the four muscles of this finger. Its form is triangular, the base looking toward the ulnar edge and the summit toward the radial edge. It arises by fleshy and tendinous fibres from the palmar face of the os magnum, and in a greater or less extent from the palmar edge of the third metacarpal bone, goes forward and outward, and is attached by a short tendon to the inner sesamoid bone.
This muscle draws the thumb toward the index finger and slightly rotates it on its axis, so that it turns its palmar face toward that of the other fingers.
§ 1178. Sometimes it divides into a posterior and an anterior belly, which are completely distinct, the posterior being the larger. In this case the first arises only from the os magnum or at the same time from this bone and a small upper portion of the third metacarpal bone : as to the second, it comes from the lower part of the anterior head of the third and fourth metacarpal bones ; sometimes also from the fifth as well as from the capsular ligament of the first phalangean articulation, and goes across or a little obliquely from before backward, to the first phalanx of the thumb, where it unites with the posterior head.
This anomaly is worthy of remark, as it coincides perfectly with the normal arrangement of the adductor of the large toe.
IV. MUSCLES OF THE LITTLE FINGER.
§ 1179. The little finger is moved by three muscles, an abductor, a flexor, and an adductor.
J. ABDUCTOR MINIMI DIGITI.
§ 1180. The abductor minimi digiti muscle, Carpophalangien du petit doigt , Ch., the shortest of these three muscles, extends along the ulnar edge of the metacarpus. It arises by short tendinous fibres from tire pisiform bone, and near the first phalanx of the finger becomes a small flat tendon, which blends with the ulnar edge of the tendon of its extensor.
It separates the little finger from the others.
II. FLEXOR MINIMI DIGITI.
§ 1181. The flexor minimi digiti muscle (JVF. flexor proprius digiti quinii ) is covered by the preceding. It arises below and before it from the pisiform bone and from the unciform process of the unciform bone : it forms a short tendon forward, which is attached to the radial side of the first phalanx of the little finger.
It flexes the little finger and separates it from the others.
It is often deficient and then the preceding is more developed.
III. ADDUCTOR MINIMI DIGITI QUINTI,
§ 1182. The adductor minimi digiti muscle, Curpo-metacarpien du petit doigt , Ch. ( J\'L adductor digiti quinii) ) is thickest and shortest, and arises from the lower anterior edge and the outer face of the unciform process of the unciform bone, goes upward, and is attached to all the ulnar face of the metacarpal bone of the fifth finger.
It carries the little finger forward and draws it toward the others, causing it to rotate around its axis on the metacarpal bone. When it acts in concert with the opponens pollicis muscle, which very much resembles it, the cavity of the palm of the hand enlarges.
§ 1183. The proper muscles of the thumb and little finger are only the lumbricales or interossei muscles largely developed and divided into several fasciculi. We must consider the flexor pollicis brevis muscle as the first lumbricalis. The abductor pollicis brevis and the opponens pollicis correspond to an external ; the adductor represents an internal interosseous muscle.
The abductor and the flexor minimi digiti muscles form only one muscle, which represents the last external interosseous muscle.
The adductor minimi digiti muscle is only an enlarged internal interosseous muscle.
Chapter II. Muscles of the Lower Extremities
§ 1184. The muscles which have with the upper section of the abdominal members relations similar to those which exist between the superficial muscles of the back and of the region of the shoulder, or the broad muscles of the abdomen, have already been examined. We may then pass immediately to those which go from the first section of the bones of the lower extremities to the femur ; but we must here also commence by describing the general aponeurotic envelop.
1. Aponeurotic 8Heath Of The Lower Extremities
§ 1185. Most of the muscles of the lower extremities, especially those of the thigh, leg, and sole of the foot, are enveloped by an aponeurotic expansion, which is not arranged every where in the same manner.
This expansion is called on the thigh the fascia lata , on the leg the crural aponeurosis, in the sole of the foot the plantar aponeurosis.
The first two form a whole more continuous with each other than with the plantar aponeurosis, and are also still more similar in their form, as they surround the thigh and the leg.
The fascia lata commences behind on the gluteæus maximus muscle, where it is very thin, and gradually loses itself at its upper portion. It arises forward from the iliac crest and from the Fallopian ligament. It ■extends as far as the knee. It adheres very intimately by the upper and external part of its anterior edge to the lower edge of the tendon of the obliquus externus abdominis muscle, to which it is much more loosely attached on its inner side.
It is thickest at the outer part and thinnest at the inner part of the thigh. It is half a line thick in every part and above even a line in the first region, while it hardly equals the twelfth of a line in the second. In general it is evidently formed of two layers of fibres : the internal is stronger and its fibres are longitudinal ; the external is weaker and its fibres are oblique downward, inward, and backward, and are more insulated, and gradually approach each other from below upward.
From the inner face of this aponeurosis arise septa which extend between most of the muscles of the thigh which they separate from each other ; we readily distinguish in most of these septa transverse and oblique fibres.
The fascia lata presents oblique fibres in every part In many
places, especially at the inner portion of its circumference, these fibres
are extended over a layer which is not evidently fibrous, especially
forward, but at the outer part this layer is manifestly formed of longitudinal fibres, and at the same time its inner face presents in different
parts more insulated oblique fibres, so that here the aponeurosis evidently consists of three layers.
The outer part of the crural aponeurosis is also much thicker, and formed in this part of two layers ; the fibres of the internal are longitudinal, those of the external, which is weaker, are oblique.
At the upper part of the aponeurosis the direction of the oblique fibres is inversely that of the oblique fibres of the fascia lata, that is, they proceed forward, downward, and inward.
At the lower part of the crural aponeurosis they have an opposite direction, and at the same time other fibres are developed on the inner side of the aponeurosis, which are oblique from behind forward and from above downward.
These outer and inner fibres cross on the anterior face of the articulation of the foot, and as they increase in strength in this part they there form the crucial ligament ( Lig . cruciaturn ), composed of two fasciculi, which cross each other in the centre. One of these fasciculi descends from the outer malleolus, goes downward and inward, and is attached to the tibial side of the first metatarsal bone. The second arises from the internal malleolus, and goes to the tuberosity of the fifth metatarsal bone.
Below, they are both continuous with the thin aponeurosis of the back of the foot, which covers the tendon of the extensor digitorum longus and the belly of the extensor communis digitorum pedis, and is lost near the anterior extremity of the metatarsus.
This aponeurosis at the back of the foot is often much stronger toward the posterior end of the first metatarsal bone in this place,where it passes over the tendon of the extensor proprius pollicis pedis,, than in the rest of its extent, and it is formed of very evident transverse fibres, which are attached internally to the inner side of the metatarsus, and outside to a special fasciculus of the extensor brevis digitorum pedis. In this case, this portion of the aponeurosis of the foot is provided with a proper tensor muscle.
II. TENSOR VAGINÆ FEMORIS.
§ 1186 . The aponeurosis of the fascia lata, like most of the aponeurotic expansions which surround the muscles, has a proper muscle called the tensor vaginic femoris muscle, llio-aponeurosi-f amoral , Ch. (M. tensor fasciœ latœ).
This muscle is situated at the anterior edge of the upper part of the lateral face of the thigh. It arises by a short but very strong tendon from the outer face of the anterior and superior spine of the ilium.
Thence it goes downward and outward, gradually enlarges, and is
continuous by very short tendinous fibres, towards the summit of the
middle third of the thigh, with the fascia lata, which is united with its
outer face more firmly than with any other muscle.
2. Muscles of the Pelvis
§ 1187. The muscles of the pelvis arise partly from its outer face, partly from its inner face, and partly from the lumbar portion of the vertebral column ; they are attached to the upper part of the femur which they extend, flex, and turn around its axis.
I. EXTENSORS OF THE THIGH.
§ 1188. The thigh is extended by three muscles called the glutœi, situated over each other ; and they cover the outer face of the iliac bones, and descend outward, downward, and forward toward the femur.
I. GLUT2EUS MAXIMUS.
§ 1189. The gluiœus maximus muscle, Sacro-femoral, Ch., is the largest of all the muscles of the body, and is nearly a regular rhomboid. It arises by its posterior and inner edge from the posterior part of the outer lip of the crest of the ilium, from the lower part of the posterior face of the sacrum, from the sacro-sciatic ligament, and from the sciatic tuberosity. It arises by these différent points by short tendinous fibres, goes from within outward and from above downward, forming a very strong and thick muscle, composed of distinct and large fasciculi which are loosely connected with each other. It is attached by a broad and very strong tendon which is continuous below with the lateral part of the fascia lata to the lower part of the large trochanter, and to the linea aspera which descend from this tubercle.
Several mucous bursae are found on the inner face of the lower tendon of this muscle. The largest and at the same time the uppermost is situated between it and the outer face of the large trochanter. Farther backward and downward we find another which is also large but a little smaller, between it the upper extremity of the vastus externus muscle and the lower end of the tensor vaginae femoris muscle. Finally, between this muscle and the femur, farther backward and downward, are two which are smaller.
The glutæus maximus extends the thigh, brings it toward the vertebral column, rotates it a little outward, and approximates it to that of the side opposite. When it acts from below upward it draws the iliac bones downward, inward, and forward.
II. GLUTÆUS MEDIUS.
§ 1190. The glutœus médius muscle, Grand ilio-trochanierien, Ch., is a large muscle, but smaller and closer than the preceding, and has a triangular form. It is covered at its posterior and lower part by the glutæus maximus, and forward by the fascia lata only, with which it is intimately connected. It arises from the outer lip of the crest of the ilium, and from the upper and anterior part of the outer face of the iliac bones which is situated between the iliac crest and the curved line. Its posterior fibres are oblique from behind forward and from without inward ; the anterior go from above downward. It proceeds towards the large trochanter, and is attached to its outer face by a broad, short, and very strong tendon, which blends with that of the glutæus maximus muscle.
A small mucous bursa exists between the upper face of this muscle, the pyrifarmis, the gemellus superior, and the inner face of the large trochanter.
The glutæus médius muscle raises the femur, separates it from that of the opposite side, and inclines the pelvis as much as possible towards its side.
Its posterior part turns the thigh outward, and its anterior turns it inward.
III. GLUTÆUS MINIMUS.
§ 1191. The glutœus miniums muscle, Petit ilio-trochanterien, Ch., has the same form as the preceding, while it is much smaller and is entirely covered by it. It arises directly below it by its upper face and anterior edge from the curved line, and from the anterior and lower part of the outer face of the iliac bones. It is attached by a short and strong tendon to the upper edge of the upper part of the inner face of the large trochanter.
A small synovial capsule exists forward between it and the large trochanter.
Its action is the same as that of the preceding.
II. MUSCLES WHICH ROTATE THE THIGH OUTWARDLY.
§ 1192. The thigh is turned outward by six muscles, the pyriformis, the obturator internus, the obturator externus, the two gemelli, and the quadrat us femoris.
I. PYRIFORMIS.
§ 1193. The pyriformis muscle, Sucro-lrochanterien , Ch. (JVT. pyriformis, pyrimidalis, iliacus externus), is a small muscle of an oblong triangular form coming from the cavity of the abdomen, where it arises by three or four digitations from the sacrum. It arises from the anterior face of this bone, between the third and fourth, the second and third, and the first and second pairs of the anterior foramina of the sacrum, , and from the inner face of the posterior and lower spine of the ilium, and from the upper part of the posterior edge of the iliac fossa. It descends through this last behind the upper part of the descending branch of the ischium, goes outward and forward, and is attached by a rounded, strong, and proportionally broad tendon to the summit and upper part of the inner face of the large trochanter.
There is a small mucous bursa between its tendon and the gemellus superior muscle.
It rotates the thigh outward, separates it from that of the side opposite, and raises it a little.
§ 1194. It sometimes divides into an upper and a lower portion, between which the glutæal nerve passes. (1)
II. OBTURATOR INTERNUS.
§ 1195. The obturator internus muscle, Sous-pubio-trochanterien interne , Ch. (AT. obturator internus , s. marsupialis, marsupialis internus ), arises from the inner face of the obturator foramen by radiating fibres, which suddenly change their direction on leaving the pelvis and turn at a right angle on the posterior face of the descending branch of the ischium, covered before by this part of the bone, and behind by the sacro-sciatic ligament. It then proceeds outward and forward, and is attached by a strong tendon to the central part of the inner face of the great trochanter, far below the tendon of the pyriformis muscle.
The arrangement of this tendon is then very peculiar. It begins within the pelvis, a short distance from the descending branch .of the ischium, but extends to about the centre of the space between the ischium and the trochanter. It does not appear except on the anterior and inner face of the muscle, where it consists of five very regular and very distinct fasciculi, two of which form the upper and lower edge of the muscle. The outer extremity of the middle belly extends between them by four triangular fasciculi, and then immediately unite in a strong tendon near the centre of the space between the ischium and the great trochanter.
We find an oblong synovial capsule backward and outward between the tendon of this muscle, the gemelli, and the great trochanter. A second, external and rounded, situated between the ischiatic spine and the great trochanter, surrounds the inner part of the tendon.
The obturator internus muscle turns the thigh directly outward and draws it from that of the opposite side.
(1) Winslow, Expos, anat., vol. ii. p. 125.
III. GEMELLI.
§ 1196. The gemelli muscles, Ischio-lrochanterien , Ch. {M. gemini femoris, marsupiales extend , marsupium ), are two small oblong muscles, which are very similar and placed one over the other : they are separated backward and outward by the tendon of the obturator internus muscle, also by that portion of this muscle which is situated out of the pelvis. Their thin edges touch forward.
The upper arises by a pointed extremity from the lower part of the posterior face of the ischiatic spine.
The lower arises by a broad and semilunar edge from the upper face of the sciatic tuberosity and from the outer face of the descending branch of the ischium. It gradually becomes thicker from within outward.
These two muscles are intimately connected with the obturator internus, especially in their outer portions, entirely cover it, and are attached with it to the inner face of the great trochanter.
They act in the same manner as the preceding.
§ 1197. The upper gemellus is frequently deficient(l) — a remarkable analogy with what is seen in the ape. (2)
We know of one case where both these muscles were deficient, as in bats.
IV. QUADUATUS FEMORIS.
§ 1198. The qnadratus femoris muscle, Jschio-sous- trochanterien, Ch., is oblong and composed of transverse fibres. It is broader from without inward than in any other direction, and its height much exceeds its thickness. It arises from the anterior edge of the sciatic tuberosity and from a small part of the ascending branch of the ischium, passes directly below the gemellus inferior to the posterior face of the femur, where it is attached to a square impression situated between the roots of the large and small trochanters above the posterior intertrochanterian line.
We find a synovial capsule between it and the small trochanter.
It acts like the preceding.
§1199. Sometimes it does not exist. (3) More rarely it is divided into several fasciculi, three of which have been known to exist. (4)
V. OBTURATOR EXTERNUS.
§ 1200. The obturator externus muscle, Sous-pubio-trochantericn externe, Ch., is a rounded and triangular muscle, at first thin, but aftcrwards it becomes thicker and again grows thinner. It arises by a rounded edge from the outer face of the ascending branch of the ischium and by short tendinous fibres from the two branches of the pubis and from the anterior face of the obturator membrane.
(1) trantzor, p. 4.
(2) Vicq. d’Azyr, Knc. méth.syst. anat. des quadrup., p. 29.
(3) Albinus, loc. c it., p. 530. — We know of one case where the gemelli were very large.
(4) Jancke, De caps. tend, arlicul., Leipsic, 1753.
After contracting considerably in its outer portion and being covered
by a broad tendon on its anterior and posterior faces, it is reflected from
the anterior to the posterior face of the body, goes obliquely upward
and outward directly behind the neck of the femur, and is attached by
a short but very strong tendon to the fossa and to the inner face of the
great trochanter, a little distance below the tendons of the obturator
internus and the gemelli muscles.
It turns the thigh outward, draws it backward toward that of the opposite side, and brings the anterior face of the pelvis to its side.
III. FLEXORS OF THE THIGH.
§ 1201. There are two flexors of the thigh, the psoas magnus and the iliacus internus muscles : to these a third is usually attached, the psoas parvus muscle ; but this does not always descend to the thigh.
I. PSOAS MAGNUS.
§ 1202. The psoas magnus muscle, Prelombo-trochanterien , Ch. (J\I. psoas magnus, s. lumbaris, s. lumbaris internus ), is a considerable elongated and rounded muscle, occupying the inner and anterior part of the lumbar region directly on the side of the bodies of the lumbar vertebra. It extends from the upper extremity of this region downward and outward to the inner face of the femur.
It arises by an external and posterior and an internal and anterior range of short, flat, and triangular slips from the five lumbar vertebra and the last dorsal.
The anterior slips come from the lateral faces of the short ligaments and the intervertebral ligaments ; the posterior arise from the lower and anterior parts of the transverse processes of the lumbar vertebra.
The belly of this muscle descends outward, covers the inner part of the iliacus internus, becomes rounded as it descends, and forms before the sacro-iliac articulation, rather outward than inward, a strong tendon which emerges from the abdomen below the crural arch behind the femoral vessels, and is attached to the anterior face of the small trochanter.
The psoas magnus muscle bends the thigh and turns it a little inward, bends the trunk and turns it a little toward its side.
§ 1203. Between this muscle and the iliacus internus we sometimes find another smaller, which arises from one or more transverse processes of the upper lumbar vertebra, proceeds on the outside of the psoas magnus muscle, and is attached to the small trochanter and sometimes to the tendon of the last. The crural nerve usually passes between it and the psoas magnus muscle.(l) This anomaly reminds us of the multiplication of the psoas magnus muscle in several apes. (2)
This and not the next muscle, as some anatomists assert, is the muscle which sometimes exists abnormally.(3)
II. PSOAS PARVUS.
§ 1204. The psoas parvus muscle, Prelombo-pubien, Ch., has an oblong square form, and arises from the lateral face of the first lumbar vertebra, and from the intervertebral ligament between it and the last dorsal vertebra, and sometimes from the twelfth dorsal vertebra. It arises generally by one but sometimes by two slips, which come either from the two vertebrae or only from the first lumbar.
Tt soon after becomes a flat and very long tendon, situated on the outside of the psoas magnus muscle, crosses it to go inward, and is attached in that part where the body of the pubis and ilium unite.
Below, the tendon becomes an aponeurosis, which covers the lower part of the psoas magnus and of the iliacus, is attached to the crural arch, and blends with the fascia lata.
This muscle bends the vertebral column forward and increases the force of the two muscles situated above it, furnishing them with a point of support.
§ 1205. It is sometimes deficient, but this is rare.
III. ILIACUS INTERNUS.
§ 1206. The iliacus internus muscle, Iliaco-troehanterien, Ch. (JVF. iliacus, s. iliacus internus ), is a broad and considerable muscle, which fills all the upper part of the inner face of the iliac bones, whence it descends to the inner part of the thigh. It arises by a semicircular and convex edge and by short tendinous fibres from the inner lip of the iliac bone, and also by fleshy fibres from the inner face of this bone to near the anterior and inferior iliac spine, goes inward and forward, becomes in its course considerably narrower and thicker, and is attached a little above the crural arch to the outside of the tendon of the psoas magnus muscle, by which it is fixed to the anterior face of the small trochanter.
We find a considerable mucous bursa between the common tendon of the psoas magnus and the iliacus internus muscle and the capsular ligament of the coxo-femoral articulation. There is another, which is smaller, between it and the small trochanter.
This muscle bends the thigh and carries it inward. It draws the pelvis and with it the trunk downward and forward.
(1) We have seen it several times. — Albinus, p. 315.
(2) Valentine, Amph. zoot., p. 151.
(3) Kelch, Bcytrœge zur path, anat., p. 22.
3. Muscles of the Thigh
§ 1207. Among the muscles which form the mass of the thigh some serve to move it and others act on the leg. Not only the first but also some of the second arise from the bones of the pelvis.
The muscles of the first class are the adductors of the thigh ; those of the second are the adductors, the flexors, and the extensors of the leg.
I. ADDUCTORS OF THE THIGH.
§ 1208. The two lower limbs are drawn toward each other by the adductors ( adductor es ), which form almost all the internal and posterior part of the muscular mass of the thigh. Three of these muscles in particular have been termed the adductors. They have been considered as forming only a single muscle, called the triceps muscle (JVf. femoris triceps ), but wrongly, as they are not united by a common tendon. The fourth has been described as a separate muscle, called the pectinœus , although it might be considered as a fourth head of the common adductor, as well as the other three.
I, PECTINÆUS.
§ 1209. The pectinozus muscle, Sous-pubio-femoral, Ch. ( JW.pecti nœus, s. pectinalis), a flat, long, quadrangular muscle, arises by its upper thin and horizontal edge from the crest of the horizontal branch of the pubis, on which its upper and anterior face passes. It goes from above downward, from within outward, and is attached by a perpendicular edge to the upper end of the inner lip of the rough line of the femur.
We find a small synovial capsule below the small trochanter, betwmen this muscle and the femur.
It draws the thigh toward that of the opposite side, raises it and carries it forward, turns it a little inward, and slightly inclines the pelvis outward and downward.
§ 1210. We sometimes find a second pectinæus, which is smaller, which blends below with the tendon of the other, and is attached above to the inner part of the upper edge of the obturator foramen.(l)
§ 1211. The three adductors, properly so called, are distinguished into the long, the short, and the great adductor.
II. ADDUCTOR LONGUS.
(1) Winslow, Expos, anat., vol. i. p. 117.
§ 1212. The adductor longus muscle, Pubio-femoral , Ch. (M. adductor femoris longus , caput primum tricipitis ), has the form of an oblong triangle. It is the second of the three adductors in size and the
longest of all. It arises by a short, narrow, but very strong tendon
from the inner part of the anterior face of the horizontal branch of the
pubis, from the spine of the pubis, and from the anterior part of the
symphysis pubis. Thence it goes outward and downward, in a direction more oblique than the preceding, becomes broader and at the same
time thinner, and is attached by a tendinous and interrupted edge to
the third quarter of the posterior lip of the rough line of the femur. Its
lower end usually unites to the vastus internus muscle.
Its action is nearly the same as that of the pectinæus.
§ 1213. It is sometimes divided into two. And again, it descends much lower, by a thin tendon united to that of the adductor magnus : so too in some mammalia and in birds the pectinæus or the other portions of the adductor muscle descend very low.
III. ADDUCTOR BREVIS.
§ 1214. The adductor brevis muscle, Sous-pubio-fcmoral, Ch., (JW. adductor femoris brevis, s. adductor secundus, s. caput alterum tricipitis), is rather a broad triangular muscle. It arises at the side of the tendon of the gracilis muscle, but much higher and more externally than it, and is closely united with its upper extremity. Its upper end, situated directly below the adductor longus and formed of very short tendinous fibres, arises from the inner part of the outer face of the horizontal branch of the pubis. It is much broader and much shorter than the preceding, goes less obliquely outward than it, and is attached to the posterior face of the small trochanter and also to the upper third of the inner lip of the rough line of the femur, by several strong tendinous slips, which succeed each other from above downward.
At its lower extremity it is connected more or less intimately with the pectinæus and the adductor magnus muscles.
It acts like the preceding.
§ 1215. It is often partially or wholly divided into two slips, which forms a remarkable analogy between man and the ape.
IV. ADDUCTOR MAGNUS.
§ 1216. The adductor magnus muscle, Ischio-femoral , Ch. (M. adductor femoris magnus, s. caput tricipitis tertium), is the largest of the three proper adductor muscles ; it also has a triangular form, the base of which rests in the thigh, and the apex looks toward the pelvis. It arises from the anterior face of the descending branch of the pubis, and is intimately connected in this part with the outer face of the lower part of the tendon of the gracilis muscle. It arises also from the ascending branch of the ischium and from the lower edge of the sciatic tuberosity.
Its upper and anterior fasciculi go directly downward and outward. The posterior and inferior on the contrary, which are attached to the sciatic tuberosity, go from below upward, around and behind the latter, so that the muscle seems at its upper part to have been twisted on itself, and is much thicker there than in the rest of its coarse.
Before the extremity of the portion inserted in the sciatic tuberosity, the upper edge, which is loose and fissured in a semilunar form, goes toward the femur, where it is attached to the posterior lip of the linea aspera, behind the pectinæus and the other two adductors, always descending deeper than they. The lower tendon is very strong, particularly at its lower part, and extends to the posterior face of the inner condyle of the femur.
About the latter fourth of the thigh this tendon is perforated by the superficial vessels of the leg, which pass from its anterior to its posterior face. It unites below to the vastus internus muscle.
T his muscle draws the thigh inward, carries it forward, turns its anterior face a little outward, flexes the pelvis forward, and directs its anterior face to the side.
§ 1217. We sometimes find it divided into two portions, as in apes.
II. MUSCLES OF THE THIGH WHICH MOVE THE LEG.
§ 1218. The muscles situated on the thigh forming its mass, and which move the leg, are distinguished into adductors, extensors, and flexors.
I. ADDUCTORS OF THE LEG.
§ 1219. Those nearest the surface are the adductors, of these there are two, the sartorius and the gracilis.
A. SARTORIUS.
§ 1220. The sartorius muscle, Uio-pretibial, Cli., the longest of all the muscles of the body, is very thin, and has an elongated square form. The short tendon by which it arises descends lower on its external than on its internal edge. It is inserted directly at the side of the tensor vaginæ femoris muscle, more inward and forward, on the anterior and upper spine of the iliac bone. Thence it passes onward and inward, above the lower part of the adductor iongus and adductor magnus muscles. In this manner it attains the anterior face of the thigh, where its lower portion goes to the inner face of the same part. Thence it proceeds directly forward and at the side of the gracilis, and soon becomes rounder and narrower, and forms a short rounded tendon which, passing behind and below the inner condyle of the femur, comes to the inner face of the leg. In this place it rests directly on the upper part of the inner face of the tibia, it becomes broader, and is at .'ached by its anterior edge to the inner face of this bone, near its sp ! ' -, and is contiguous below with the aponeurotic expansion of the leg.
This muscle flexes the knee, and when this articulation is bent it turns the tibia inward, so that the end of the foot approaches the other. When it acts in an opposite direction it draws the haunch a little forward and turns it inward.
§ 1221. We have met with one subject in which the sartorius muscle did not exist.
Sometimes, on the contrary, there are two which may happen in several different ways.(l) The normal muscle usually appears curved inward, and the additional muscle terminates sooner below, where it is attached either to the tendon of the first or to the femur.
Sometimes the fibres of the sartorius muscle are interrupted by a considerable intermediate tendon which is firmly united to the fascia lata. (2)
B. GRACILIS.
§ 1222. The gracilis muscle, Sous-pubio-pretibial , Ch. (JM. gracilis, s. rectus internus), is a thin muscle of an oblong triangular form which arises by abroad base which forms its upper edge, from the anterior face of the lower portion of the descending branch of the pubis, and from the upper part of the ascending branch of the ischium. Thence one of its edges turns forward and the other backward, one of its faces outward and the other inward ; it goes to the inside of the thigh, and above its latter sixth, becomes a thin and rounded tendon, which proceeds directly behind the lower part and the tendon of the sartorius, and turns with it on the inner condyle of the femur. • It is at first covered by it, and is then situated below it, and blended with it in its anterior and inferior part, and is finally inserted a little lower down, in the upper part of the inner face of the tibia.
It bends the knee, turns the leg inward, and draws the anterior face of the iliac bones from the side to which it is attached.
II. EXTENSORS OF THE LEG.
§ 1223. The leg has four extensors which may very properly be considered as one muscle with four heads, since they are attached to a common tendon. They are situated directly below the fascia lata aponeurosis on the anterior face, and on the sides of the thigh, and form most of its muscular mass. A considerable mucous bursa exists between them and the aponeurosis of the thigh. They are termed the rectus femoris, the vastus internus, the vastus externus, and the cruræus muscles.
A. RECHTS FEMORIS.
§ 1224. The rectus femoris muscle, Jlio-rotulien, Ch. {M. rectus femoris, s. extensor cruris médius superficialis), is a strong elongated pointed muscle situated on the anterior face of the thigh, directly under the fascia lata aponeurosis in most of its length, except its upper part, where it is covered by the sartorius muscle.
(1) Huber, Act. n. c., vol. x. p. 114.— Rosenmüller, loc. cit., p. 7.— Gantzer, p. 14. '
(1) Kelch, loc. cit., p. 42, p. xxxv.
It arises by two points from the iliac bone by a very strong but short
tendon. In fact, this tendon is divided above into two heads, an upper
and a lower or external tendon.
The upper head, which goes directly downward, comes from the anterior and inferior spine of the ilium. The lower, which is curved in a semicircle, arises from the upper part of the edge of the cotyloid cavity. These two heads soon unite to give rise to the upper common tendon. This tendon soon disappears on the posterior part of the muscle, but becomes much broader on the anterior, and descends to its centre, gradually becoming thinner.
The central fleshy portion is composed of an outer and an inner layer of fibres, which unite at an acute angle on the median line, so that the arrangement of these fleshy fasciculi resembles in some measure a roof.
The fibres are much longer, and ascend much straighter the nearer they are to its lower extremity. They are attached on both sides to a prolongation of the upper tendon, the direction of which is from before backward, which descends into the substance of the muscle from its anterior face, and gradually diminishes from above downward. It however continues perceptible to near the lower end of the fleshy belly, that is, much lower than the broad and anterior part of the upper tendon descends on its outer face. It is nowhere connected with the posterior and inferior tendon.
The lower tendon is much longer but is weaker than the upper. It ascends on the posterior face of the muscle, much higher than the upper, descends on the anterior, so that the fleshy belly is situated for several inches before and behind between two tendinous expansions. It begins to be visible forward only towards the lower third of the thigh, and is seen first on the two sides of the fleshy belly, which gradually contracts. It is entirely loose after quitting the last fifth of the thigh. When approaching the patella below, it becomes broader, and is attached to the upper edge of this bone, and is intimately united with the tendons of the other extensors.
This muscle extends the leg when the thigh is fixed, and the thigh when the leg is fixed ; in the latter case it also bends the pelvis a little and turns its anterior face obliquely to the opposite side.
B. VASTUS EXTERNUS.
§ 1225. The vastus externus muscle, ( JVL . extensor cruris vastus, s. externus), ( 1) the largest of all the extensors of the leg, although much shorter than the preceding, forms almost solely the muscular mass on the outside of the thigh ; at the same time it extends very much backward and forward. It is considerably thick, but it is broader from before backward than from within outward.
(1) This and the next two muscles are termed the Trifemoro-rotulien by Chaussier.
It arises by a slightly concave edge which inclines from before backward, from within outward, and from above downward, from the lower
part of the anterior and outer face of the great trochanter. The
upper half of its posterior edge, situated along the rough line of the
the femur, comes from the inner face of the outer wall of the fascia lata
aponeurosis. From all these points it gradually descends forward,
becomes narrower, and is finally attached, by an inferior tendon, to the
upper and outer edge of the patella. The inner part of this tendon is
covered some distance above its insertion by the tendon of the rectus
femoris muscle, to which it is even slightly united, although it is easily
separated from it as far as where it is inserted in the patella.
The muscular fasciculi go directly downward. The upper tendon extends below the centre of the muscle on its outer face, and the lower only to the centre of its inner face.
The vastus externus muscle extends the knee,- and most generally raises the leg at the same time, and turns it a little outward.
C. VASTUS INTERNUS.
§ 1226. The vaslus interims muscle (JVf. extensor cruris , s. vastus interims ) is a little shorter and much weaker than the preceding, with which it is blended outwardly in a small portion of its upper extremity. It arises by its upper edge, which descends obliquely inward, from the anterior intertrochanterian line ; by a small part of its lower edge, from a part of the anterior face of the femur situated below this fine ; and by the upper part of its posterior edge, from the upper part of the anterior lip of the linea aspera. Its lower tendon is attached to the inner part of the upper edge, and to the inner edge of the patella. The inner part of this tendon is covered below by that of the vastus externus which passes obliquely over it, and is attached to the patella before it ; it adheres to this tendon, but is easily separated from it.
The upper tendon of this muscle descends over almost the whole of the inner and loose face on the posterior half of the muscle, while the lower disappears already below the centre of its outer face, principally at its upper part.
This muscle extends the leg and turns it a little inward.
D. CRURÆUS.
§ 1227. The crurczus muscle, (JVT. cruralis, s. crurœvs , s. femorceus) the shortest of the four extensors of the leg, is also nearly as strong as the preceding. It arises by its posterior and inner face, directly below this last, from the larger part of the anterior and the outer face of the femur, excepting a small portion above, and from its lower third. The posterior edge comes from the outer lip of the linea aspera. This muscle covers also most of the anterior and outer faces of the femur. It is attached by its lower tendon behind the vastus internus and the vastus externus to the upper edge of the patella, and usually also at its lower and outer part, by short fibres, to the synovial capsule, and to the outer edge of the patella.
This lower and outer part is generally separated from the others, particularly from their tendon.
The upper edge of this muscle is attached to the bones without any appearance of a tendon. The lower tendon, the loose portion of which is longer than that of the two preceding, begins on the contrary from the middle of the anterior and loose face.
The cruræus muscle is mostly covered above by the vastus externus and the vastus internus ; it is entirely covered below by the rectus muscle, excepting however its outer and lower lateral face, where it is concealed by the vastus internus muscle. Its lower part also is intimately connected with the two vasti, especially the externus.
A capsular ligament exists between its tendon, that of the vastus externus, the capsular ligament and the patella ; this frequently opens into the femoro-tibial articulation.
It extends the knee.
§ 1228. The common tendon of these four muscles, after enveloping the patella, goes to attach itself to the tuberosities of the tibia, where we find a considerable synovial capsule between it and the bone.
E. 6UBCRÃœEALIS.
§ 1229. The subcruralis muscle is a small triangular muscle, which always exists and is entirely covered by the lower part of the preceding. It arises from the lower fourth of the anterior face of the femur, and is attached to the upper part of the anterior wall of the synovial capsule of the knee. It draws this capsule in the motion of extending the leg, and also prevents it from being injured.
III. FLEXORS OF THE LEG.
§ 1230. The flexors of the leg are situated on the posterior face of the thigh. We number three, two internal and an external ; but the latter arises by two heads. All arise at the side of each other from the sciatic tuberosity, and are attached posteriorly to the bones of the leg. They consequently bend the knee or draw the posterior faces of the thigh and of the leg towards each other. They also extend the coxo-femoral articulation when the leg is extended.
I. INTERNAL FLEXORS.
§ 1231. The two inner or tibial flexors arise from the sciatic tuberosity and are inserted in the upper end of the tibia. They are called the semimembranosus and the seimtendinosus.
A. SEMITENDINOSUS.
§ 1232. The semitendinosus muscle, Ischio-pretibial, Ch. (JVf. semitendinosus , s. seminervosus ), is an elongated muscle broader and thicker above than below, partially covering the following, because it is extended more below it and nearer the surface. It arises from the inner part of the posterior face of the sciatic tuberosity by a tendon which is very distinct outwardly, while its summit adheres very intimately to the inner edge of that of the long head of the biceps femoris muscle. This muscle is the most internal of the three flexors, and goes directly downward. Its lower tendon commences on its inner edge, a little below the centre of the fleshy belly ; from about the last fourth of the thigh it forms a very strong rounded cord, which passes behind the inner condyle of the femur to arrive at the tibia, and is attached, after enlarging and becoming thinner, to the inner face, directly below the gracilis muscle. It blends with the lower edge of the tendon of this latter muscle, and generally divides below into an upper and a lower slip.
We find a mucous bursa directly near its insertion, between its upper tendon and that of the semimembranosus and the long head of the biceps. There is also another, and sometimes two or three, even between its lower tendon ; that of the sartorius, that of the gracilis, and the internal lateral ligament of the knee.
This muscle bends the leg and turns it a little inward ; when it acts in an opposite direction it draws the pelvis and the trunk backward, and bends them with the thigh in the same direction.
B. SEMIMEMBRANOSUS.
§ 1233. The semimembranosus muscle, Ischio-poplili-tibial, Ch. (AT. semimembranosus ), follows a direction to a certain exent directly opposite to that of the preceding. Of the three flexors this arises farther forward, upward, and outward from the outer part of the sciatic tuberosity by a very long, strong, broad, and perfectly distinct tendon, which gradually enlarges and becomes thinner as it descends to the centre of the thigh and to the end of the fleshy belly, to which it is united by an edge oblique from within outward. This belly is elongated, rounded, thicker, but shorter than that of the semitendinosus, and is formed of an internal and an external layer of fibres which are turned upward towards each other, and are attached by radiations to the upper tendon. This latter exists only on the outer face of the upper part of the muscle ; but from its centre to its lower end, where it appears externally as a narrow band, it penetrates deeply inward to the centre of its substance. The lower tendon, which proceeds nearly to the centre of the muscle on its anterior face and on its inner edge, passes on the outer face of the inner condyle of the femur, between it and the semitendinosus muscle and is inserted to the inner part of the inner condyle of the tibia, after passing freely a short distance.
A mucous bursa exists between the upper tendon and the quadratus femoris or the adductor magnus. Sometimes there are two. Another is found between the lower tendon, the upper internal head of the gastrocnemius and the capsular ligament of the knee. This bursa often encloses another which is smaller, and adheres very intimately to the tendon of the semimembranosus muscle.
The action of this muscle is the same as that of the preceding.
II. BICEPS FEMORIS.
§ 1234. The biceps femoris muscle, Ischio-femoro-peronier, Ch. (JVJT. flexor cruris externus , s .fibularis, s. biceps femoris ), arises above by two separate heads, which are attached below by a common tendon.
The long head arises from the posterior face of the sciatic tuberosity by a short but firm tendon, which is inserted between the two preceding muscles. A short distance from its upper extremity this tendon begins to receive the fasciculi of the fleshy belly, and descends along its inner edge. The belly descends at first in a straight line, behind and at the side of the upper part of the semimembranosus muscle ; but it then goes outward, passes over the adductor magnus, and thus arrives at the outside of the thigh.
The short head is much smaller, and its form is an oblong square. It arises by very short tendinous fibres from the central two fourths of the outer lip of the linea aspera, directly at the side of the adductor magnus, goes obliquely downward, and is attached tothe inner face of the lower tendon of the long head, from the lower fourth of the thigh to near its lower end.
The common inferior tendon, which goes nearly to the centre of the large belly, on its posterior face, descends on the outer face of the outer condyle of the femur, and is inserted at -the top of the head of the fibula, where there is a mucous bursa between it and the external lateral ligament of the knee.
The biceps femoris muscle bends the knee, turns the leg a little outward, extends the pelvis, and inclines it slightly downward and backward.
§ 1235. Sometimes the short head does not exist, a remarkable analogy with animals, in most of which it is deficient. But in other subjects we find a third, which is thinner, and comes sometimes from the sciatic tuberosity, and is attached below the common tendon of the muscle,(l) and sometimes arises from the upper part of the long head, descends on the calf of the leg, and is joined by the lower end to the tendo Achillis ;(2) this deserves to be remarked because the biceps femoris muscle descends very low in the mammalia.
(1) Gantzer, loc. cit., p. 15. — Scenamering', Muskelehre, p. 276.
(2) Kelch, loc. cit., p. 42, no. xxxvi.
When this anomaly exists the biceps femoris resembles the normal structure of the biceps flexor cubiti, even as the latter, when it presents a third supernumerary head, represents the anomaly, of which the other sometimes gives an instance.
4. Muscles of the Leg
§ 1236. The muscles of the leg occupy its posterior, external, and anterior faces ; but they leave the internal loose, so that on this side the tibia is covered only by the skin. Most of them are attached, by their upper extremities, to the bones of the leg, and by their lowrnr, to those of the feet as far as the toes. Some, however, come from the lower part of the thigh, their lower extremities are inserted in the bones of the leg.
I. POSTERIOR MUSCLES.
§ 1 237. The posterior muscles of the leg form two layers, a superficial and a deep layer.
I. SUPERFICIAL LAYER.
§ 1238. The superficial layer of the posterior muscles of the leg is composed of two muscles, the triceps suræ and the plantaris.
A. TRICEPS SUBS.
§ 1239. The triceps suræ muscle {JM. triceps suræ , s. gemelli cum soleo) is extremely strong, and forms most of the muscular mass of the leg ; it deserves to be considered as a separate muscle with three heads, since these heads, although entirely separated above, are all attached below to a common tendon.
Two of these heads are in pairs and the third is single. The first two called for this reason the gastrocnemii muscles, Bi-femoro-calcaniens , Ch. (JM. gemelli suræ), are situated at the side of each other. They arise by a short, broad, but thin tendon, which terminates above by a semicircular convex edge from the femur, above the upper edge of the posterior face of its inner and outer condyle.
These two bellies are triangular and much narrower above than below. Above there is an interval of about four inches, which is filled by an abundant and very loose cellular tissue and also by the vessels and the nerves of the leg. Their fibres converge from above downward and meet the common tendon a little above the centre of the whole length of the muscle. The upper tendon, which is expanded along the external edge and the posterior face, gradually becomes thinner and descends almost to the lower extremity of the fleshy belly. The latter terminates below in a rounded edge ; so that the two bellies unite and form a waved line, very concave in its central part. The inner belly is much stronger and descends much lower than the outer. The lower tendon, in which the two fleshy bellies are inserted, arises far above their anterior face, that which corresponds to the posterior face of the bones of the leg, from the union of the two bellies to the centre of their common lower edge : it forms a broad canal, through which • pass the branches of the nerves and vessels which descend on the posterior face of the loose portion of the common tendon.
The third belly, called also the solans muscle, Tibio-calcanien, Ch., is much stronger than the two preceding. It is situated below and before them.
It arises by its upper edge, which is fleshy, serrated, and oblique downward and inward, from the posterior part of the head of the fibula, from the lower edge of the poplitæus muscle, and from the posterior edge of the tibia. Its lower edge and a part of its anterior face arise for a considerable distance above from the posterior face and below from the inner edge of the tibia. Finally, its outer edge comes from the upper part of the posterior face and from the outer edge of the fibula.
Its posterior and upper fasciculi go directly downward. The anterior and inferior of the two sides meet each other below and are attached to the anterior face of the common tendon, covering its anterior face to some inches above its insertion, gradually becoming thinner and narrower, so that this belly consequently occupies nearly all the leg, and descends very much lower than its centre.
The tendons by which the two lateral edges of this muscle arise from the fibula and the tibia gradually enlarge, descend on the anterior edge and on the posterior face, and do not stop except at some’inches above the lower end of this fleshy belly. Hence most of the latter is enclosed between two aponeurotic expansions.
The common inferior tendon, called the Achilles tendon ( tendo Achillis ), from its power, is slightly covered above and behind by the two posterior bellies and before by the third belly. A little above the lower edge of the posterior bellies it divides into an anterior and a posterior tendinous layer. The latter reascends on the anterior face of the gastrocnemius in the manner mentioned above : the other covers the posterior face almost to the upper edge, gradually becoming thinner.
The tendon, considered as a whole, contracts very much from above downward, and also becomes thicker, and is attached by a very narrow edge to the upper part of the posterior face of the tubercle of the calcanéum, between which and its anterior face we find a considerable mucous bursa above its insertion.
The triceps extends the foot in raising the heel : hence why it acts principally in standing on the toes and other similar circumstances.
When the foot is fixed, the two upper heads bend the knee and r draw
the thigh backward and downward. The lower head, when it contracts toward the heel, extends the foot, because it carries the leg downward.
This muscle corresponds to the supinators and to the pronator quadratus of the fore-arm : the two superficial heads represent the supinators and the deep head is analogous to the pronator.
B. PLANTABIS.
§ 1240. The plantaris muscle, Petit femoro-calcanien, Ch., arises by a short tendon from the posterior face of the external condyle of the femur, from the external head of the gastrocnemius muscle, to which it is united, and from the posterior wall of the synovial capsule. Proceeding directly behind the capsule, it goes inward and downward and even becomes a long, thin, and flat tendon, which descends along the inner edge of the tendo Achillis, unites with it below, and disappears in the cellular tissue on the inner face of the calcanéum to arrive at the tendinous expansion of the sole of the foot.
This muscle has no very manifest action. We see in it only a rudiment of that which is much more developed in some mammalia and an imperfect imitation of the palmaris brevis of the hand.
§ 1241. It is often deficient and much more frequently than the palmaris.(l)
II. DEEP LAYER.
§ 1242. The deep layer of the posterior muscles of the leg is composed of the poplitæus, the tibialis posticus, the flexor longus digitorum communis, and the flexor longus pollicis proprius.
A. POPLITÆUS.
§ 1243. The poplitæus muscle, Femoro-popliti-tibial, Ch. (J\I. poplitœus , s. sub poplitæus), is a triangular muscle, which arises from the inferior and posterior part of the outer face of the external condyle of the femur. It is formed of oblique fibres, becomes broader from without inward, and is attached to the upper part of the posterior face of the tibia. It is intimately connected, especially at its upper and outer part, with the posterior wall of the synovial capsule of the knee. We find a mucous bursa between it and the external condyle of the femur on one side, the external semilunar cartilage and the capsular ligament on the other.
(1) Our observations authorize us to assert that Gantzer mistakes in stating that the plantaris is more constant than the palmaris (toe. cit., p. 4).
This muscle corresponds to the pronator teres of the fore-arm.
It turns the leg a little inward, draws the outer semilunar cartilage outward and backward, and contributes to bend the knee.
§ 1244. Sometimes it is double.(l)
S. TIBIALIS POSTICUS.
§ 1245. The tibialis posticus muscle, Tibio-sous-tarsien, Ch. (AI. tibialis , s. tibiœus posticus , s. nauticus ), arises between the extensor digitorum communis longus and the flexor longus pollicis pedis (§ 1248). It is the longest of the three muscles of the deep-seated lajmr and is penniform. It arises in its whole length from most of the posterior face of the interosseous ligament and from the inner face of the fibula ; some fibres of its upper part arise also from the outer part of the posterior face of the tibia.
Even as in the two long flexors of the toes, the two layers of fibres are attached to a very strong tendon, which descends inward and forward, is contained within the posterior and fibro-cartilaginous groove of the internal malleolus, thence passes into an analogous groove hollowed along the upper part of the inner face of the astragalus, and thus goes to the inner and lower face of the sole of the foot, opposite thd anterior part of the inner face of the astragalus. Its tendon incloses a rounded sesamoid bone and divides into two slips : the internal is shorter, the inferior is longer.
The first is single and is attached to the inner edge of the scaphoid bone. The second divides into several bands, which are inserted in the lower face of the scaphoid, the cuboid, and the three cuneiform bones, at the same time that they blend with the aponeurotic expansion of the sole of the foot and with the tendon of the peroneus longus.
The tendon of this muscle is surrounded with a mucous sheath where it arrives at the sole of the foot.
This muscle corresponds to the radialis internus muscle (§ 1149).
It extends the foot, turns its inner edge a little upward, and the sole inward ; it also extends the thigh and draws it backward.
C. FLEXOR LONGUS DIGITORUM COMMUNIS.
§ 1246. The flexor longus digitorum communis muscle, Tibio-plialangettien , Ch., (AI. flexor digitorum communis longus , s. perforons, s. profundus ), is a thin, elongated, and penniform muscle ; it arises from the summit of the anterior face of the tibia, except its upper part, which is covered by the poplitæus. The fasciculi, by which it arises, and which converge downward are inserted in a strong tendon below, which ascends almost to the upper extremity of the muscle and proceeds along the inner edge. This tendon approaches the surface, descends on the posterior face of the tibia, goes to the inner face of the tarsus, and enters a fibro-cartilaginous furrow which exists along the upper part of the inner face of the astragalus, and is there kept in its position by a tendinous sheath, and thus goes forward. After leaving this point it turns outward, is covered by the posterior head of the abductor pollicis pedis muscle, on which it continues to go forward, and soon divides into fouibands, which go in their turn on the flexor digitorum brevis, which is consequently covered by it.
(1) Fabricius, De motu loculi animalium, in Op., p. 359.
At the place where the tendon of the flexor longus muscle passes on
the flexor brevis, and before it divides into four bands, we see a small
muscle attached to its external and inferior part. The form of this
muscle is an oblong square. It may be called the small or accessory
head of the flexor longus communis {accessorius perf or antis).
This small head, which is covered on all sides by the flexor communis digitorum brevis, arises by two slips, the posterior or external, which is longer and stronger and comes from the external anterior tuberosity of the calcanéum, and the anterior or internal, which is smaller and arises from the superficial calcaneo-cuboid ligament (§ 982). Its fibres are oblique. It goes forward and inward, and not only is it fitted by its inner edge to the tendon of the flexor digitorum longus, but contributes much by its anterior tendons to form those of this muscle.
The small head principally forms almost the whole tendon of the second toe. Most usually this tendon is not at all derived from that of the slip of the common flexor, but only from the short head and from the tendon of the extensor longus proprius pollicis, with which the centre of the flexor communis communicates near the anterior extremity of the calcanéum.
The tendons of this muscle have the same relation to those of the short flexor as those of the flexor digitorum sublimis have with those of the flexor profundus. They are situated upon them, perforate them above the second phalanx of the toes, enlarge a little, and are attached to the posterior part of the lower face of the third phalanges.
It is surrounded by a mucous sheath in the place where its tendon passes at the side of the fibula and of the calcanéum. A second envelops this tendon and that of the flexor longus pollicis proprius at the posterior extremity of the sole of the foot.
The tendon it gives to each toe and that of the flexor minimi digiti proprius are surrounded with a proper mucous sheath.
This muscle bends the third phalanx of the toes and brings the leg backward.
§ 1247. Sometimes it is furnished with a fifth tendon, which replaces the fourth of the flexor digitorum brevis, which is then deficient. This tendon proceeds along the inner edge of the fourth tendon of the flexor longus, and divides to allow the latter to pass, and consequently presents the same arrangement as the flexor sublimis.(l) This formation evidently resembles that of the apes, in which the tendons of the flexor sublimis and flexor profundus are so blended that they are distinguished from each other with difficulty.
(1) Brugnone, loc. cit., p. 176.
D. FLEXOR LONQUS POLLICIS FKOPHIUS.
§ 1248. The flexor longus pollicis proprius muscle, Peroneo-sousphalangettien du pouce, Ch. (JVI. flexor hallucis longus), is shorter but much stronger than the preceding. It arises by an internal and an external layer of fibres, which converge downward and proceed by fleshy fibres from almost all the lower half of the posterior face and from the outer edge of the fibula, excepting only its lowest portion. These two orders of fibres are inserted in a strong lower tendon, which mostly remains concealed in the midst of the muscular substance and becomes entirely loose only when its fleshy fibres cease. This tendon goes obliquely from without inward and from behind forward, and thus comes on the inside of the tarsus, whence it goes forward along a fibrocartilaginous groove, which exists at the upper part of the inner face of the calcanéum, directly below the upper edge of this bone, and where it is retained by a special sheath. It is covered by the outer slip of the posterior head of the abductor pollicis pedis muscle and directly by the tendon of the flexor communis digitorum longus which is nearer the surface, and is consequently situated beneath it. It crosses the direction of the latter and sends to it a very strong tendon, which unites principally to that of the second toe.
We may justly say that the tendon of the flexor longus pollicis proprius muscle divides into two slips where it passes under the abductor pollicis pedis, an external for the second toe and an internal for the large toe. The latter is the strongest ; it goes inward and forward directly at the side of the abductor pollicis pedis, is situated outward before it, and is partly covered by it. At the anterior end of thé metatarsal bone of the large toe it enlarges a little, at the same time becomes thinner, and is attached to the posterior part of the lower face of the second phalanx of the large toe.
This muscle corresponds to the flexor longus digitorum communis in its course and in its attachment to the anterior phalanx of its toe.
There is in fact a short flexor of the large toe ; but this muscle has no perforated tendon which is attached to the posterior phalanx. On the contrary, we sometimes see an arrangement analogous to that of the tendons of the flexor brevis perforatus. In fact a strong but narrower tendon, which however gradually enlarges as it advances, extends from the head of the first metatarsal bone to the posterior end of the second phalanx, over the tendon of the flexor longus : this tendon is firmly attached in its whole extent and breadth of its upper face to the lower face of the phalanges, by a fold of the synovial capsule : it contains a single and transverse sesamoid bone : immediately behind its anterior extremity and below the articulation of the first phalanx with the second, it is finally attached to the lower face of the first phalanx, directly behind the tendon of the flexor longus.
This tendon which has no muscle, is not found in the other toes ; so that decidedly we should consider it as a rudiment of the flexor longus communis perforatus : it is however but an imperfect rudiment, since it is never perforated, which depends probably on the absence of the second phalanx of the large toe.
The tendon of this muscle is enveloped with a mucous bursa in the canal of the astragalus and os calcis. A second covers its tendon and that of the flexor longus at the posterior part of the sole of the foot. A third incloses its tendon along the metatarsal bone of the first toe.
It flexes the large and small toe.
§ 1249. We sometimes find at the lower part of the posterior face of the leg a small supernumerary muscle, which does not always present exactly the same arrangement. Sometimes it ascends from the calcanéum and from the tendo Achillis, and is attached to the aponeurotic expansion of the leg, acting as its tensor muscle ;(1) so that we may then consider it as a fourth head of the triceps. It sometimes arises from the lower part of the fibula, goes downward, and is then lost around the articulation of the foot. It is sometimes attached to a special bone found in this place, (2) or to the lower face of the calcanéum, or finally to the small head of the flexor longus digitorum communis. (3)
The second anomaly is very probably a repetition of the pronator quadratus of the upper extremity, but it is developed lower toward the foot, in accordance with the same law as that to which the other muscles are subjected, especially the flexors and extensors of the toes.
The first corresponds probably to the palmaris brevis ; the arrangement of the muscle in the upper and lower extremity differ in the same way as the palmaris brevis and the plantaris, as the latter does not arrive at the aponeurotic expansion of the sole of the foot.
II. EXTERNAL MUSCLES.
§ 1250. The external muscles of the leg are the peroneus longus and the peroneus brevis. They extend from the fibula to the outer edge and to the lower face of the foot.
I. PERONEUS LONGUS.
§ 1251. The peroneus longus muscle, Peroneo-sous-tarsien, Ch. (JM. 'peroneus longus, s. primus, s. posticus ), arises from the upper and smaller half of the anterior face, and by fibres which proceed obliquely from above downward and converge. Its upper tendon arises from the outer edge of the fibula and covers the upper and posterior part of this bone.
(1) Mayer in Heymann, loc. cit ., p. 15.
(2) Rosenmüller, loc. cit., p. 8.
(3) Gantzer, loc. cit., p. 15-17.
The lower tendon, which is very long, very strong, flat, and entirely
loose from the lower third of the leg, conceals itself partially above this
point between the muscular fibres ; so that it entirely disappears externally toward the bottom of the upper third of the leg. But it appears
again within the muscle, near its upper extremity, as a semicircular
band, which gradually diminishes and to which the fleshy fasciculi are
attached outward and inward.
This tendon goes behind and on the outside of that of the peroneus brevis, along the outer and posterior face of the leg, and descends behind the external malleolus across a ligament formed of oblique fibres, within which is a sheath which sends prolongations to it. Arrived at the foot, the tendon winds forward and downward, 'around the outer edge of the cuboid bone, and thus comes on the sole of the foot, where it penetrates ; thence it goes inward, covered by all the muscles of this region and directly by the calcaneo-cuboid ligament, which keeps it in place : then gradually enlarging, it is attached to the lower face of the cuboid bone and also to the lower face of the posterior head of the fifth, also of the fourth and third, and particularly of the second metatarsal bones : it sometimes also reaches the first metatarsal bone and the first cuneiform bone before dividing.
At the place where the friction of the tendon is the greatest, especially opposite the external malleolus, the tuberosity of the calcanéum, and the cuboid bone, sometimes also in its plantar portion, we find sesamoid bones or cartilages, the third of which is the largest, while the first is very small and often scarcely perceptible.
There is also a considerable mucous bursa where the tendon of the muscle descends on the outer malleolus and astragalus : this bursa envelops it and also the tendon of the following muscle. We find another below, which extends to the plantar face.
The peroneus longus muscle extends the tibio-tarsal articulation and chaws the foot backward and the leg downward : it also turns the foot, making its outer edge the upper and the plantar face look upward.
It corresponds to the flexor carpi ulnaris of the fore-arm.
II. PEEONEUS EEEVIS.
§ 1252. The peroneus brevis muscle, Grand peroneo-sus-metatarsien, Ch. (JV[. peroneus, s.fibidaris brevis, s. anticus, s. secundus, s. médius, s. semifibulœus ), is an elongated muscle, which terminates above in a point and is formed of two layers of fibres ; those of the anterior layer go from before backward and those of the posterior go from behind forward, These two layers converge toward the base : they arise from the second fourth of the anterior face and from the posterior edge of the fibula to near the outer malleolus.
The lower tendon, which is long, strong, and flat, extends within the muscle, and like that of the preceding ascends almost to its upper extremity. It becomes visible externally sooner than that of the peroneus longus, and descends between the fibres of the muscle to arrive at its outer face.
Once disengaged it goes before that of the peroneus longus, behind the outer malleolus, and is retained in the groove which exists there by a ligament, common to it and the preceding muscle. This ligament, called the retinaculum musculorum peronœorum, extends from the anterior to the posterior edge of the groove like a bridge. The tendon having thus reached the upper face of the foot goes forward, enlarging along its anterior edge. Near the base of the fifth metatarsal bone it usually divides into two slips, the outer of which is attached to the tuberosity of this bone while the inner is longer, subdivided likewise into two parts, one of which is attached to the centre of the upper face of its body ; the second is inserted partly in the outer edge of the fourth tendon of the extensor and partly on the posterior face of the fourth external interosseous muscle.
Besides the common mucous bursa (§ 1229) the tendon of this muscle has a special bursa situated lower on the outer edge of the foot, and which surrounds it.
The peroneus brevis muscle acts like the preceding ; it flexes the tibio-tarsal articulation, consequently carries the foot upward, and depresses the leg ; it also turns the sole of the foot outward and its outer edge upward, but less so than the peroneus longus.
It corresponds to the extensor carpi ulnaris, and paitially also to the extensor brevis minimi digiti.
§ 1253. It is sometimes double.
III. ANTERIOR MUSCLES.
§ 1254. On the anterior faco of the leg we find one after another the extensor longus digitorum communis, the extensor longus hallucis proprius, and the tibialis anticus.
I. EXTENSOR LONGUS DIGITORUM COMMUNIS.
§ 1255. The extensor longus digitorum communis muscle, Peroneosus-p halange men commun , Ch. ( AI. extensor digitorum communis longus ), is a very long muscle, occupying almost all the leg. Its fibres descend obliquely from behind forward. It arises above from the outer face of the head of the tibia, and, in the rest of its course, from the anterior face of the interosseous ligament, and also from the anterior edge of the fibula. It is attached to the tendon which commences near its upper extremity and which descends on its anterior edge.
This tendon generally divides below the crucial ligament of the foot into five slips, which separate from each other. The outer is the shortest, and is inserted into the posterior extremity of the upper face of the fifth, and sometimes also of the fourth, metatarsal bone. This slip is sometimes connected with a special fleshy belly entirely distinct from the extensor longus, but which most generally forms only the lower part, and which is called the small or the peroneus iertius muscle. It is not unfrequently deficient, and is then replaced to a certain extent by the inner part of the tendon of the peroneus brevis muscle : it also frequently forms a small special tendon which is sometimes attached forward to the metatarsal bone, and sometimes unites either to the fourth external interosseous muscle or to the tendon sent by the common extensor to the fifth toe. The four other slips go obliquely forward and outward ; they are attached to the dorsal faces of the second, third, fourth, and fifth toes. Arrived at the base of the posterior phalanges they become broader and a little thinner, and give off also, the fourth outwardly, the other three inwardly, a thin triangular prolongation, formed of perpendicular fibres, which go downward, and are attached partly to the base of the first phalanx, and are partly blended with the tendon of the interosseous muscles.
This tendon sometimes assumes the nature of cartilage when passing over the synovial capsule of the first phalangean articulation. On the articulation between the second and third it enlarges or divides more or less completely into two lateral slips, which converge forward, and after muting are attached to the upper face of the third phalanx, directly before its posterior edge.
We find an oblong mucous bursa on the articulation of the foot, between the tendon of this muscle and the capsular ligament.
The extensor digitorum communis longus raises the four smaller toes, extends them, and with the peroneus brevis muscle, bends the tibiotarsal joint, and thus raises the foot or draws the leg forward and downward.
This muscle and the preceding act principally in standing on the toes, because they fix the leg.
The extensor digitorum communis longus corresponds to the common extensor of the fingers. The proper extensor of the little finger is represented by the peroneus tertius, and when that is deficient by a part of the peroneus brevis.
This analogy becomes still more evident when the portion of the flexor longus belonging to the little toe, and the peroneus tertius muscle, are entirely separated from the rest of the muscle.(l)
II. EXTENSOR LONGUS HALLUCIS EROPRIUS.
§ 1256. The extensor longus hallucis proprius muscle, Peroneo susphalangettien du pouce , Ch., is a thin and semipenniform muscle, which arises, by fleshy fibres, from the lower two thirds of the inner face of the fibula, and from the anterior face of the interosseous ligament. It also receives below some fibres from the outer face of the tibia.
Its fasciculi are attached to a tendon which proceeds along the anterior edge of the muscle, gradually becomes broader, passes across a particular groove of the crucial ligament of the back of the foot, goes inward and forward along the inner edge of the tarsus, and is attached to the upper face of the unguæal phalanx of the first toe.
(1) Brugnone, loc. cit . — We have seen it several times.
On the back of the tibio-tarsal articulation the tendon of this muscle
is inclosed in a special mucous sheath.
It raises all the first toe.
§ 1257. This muscle is often more or less completely double. In this case we sometimes find another which is smaller, and which arises more externally from the fibula, and from the anterior face of the interosseous ligament, goes to the large toe, and unites to the tendon of this muscle, or is attached to the first metatarsal bone, or finally loses itself in the cellular tissue. Sometimes and most generally another smaller tendon is detached, even in the leg, from the inner edge of the normal tendon, which is inserted in the tibial side of the two phalanges. These anomalies are important because they approximate the formation of the proper extensor of the large toe to that of the proper extensor of the thumb ; so too on the other hand, the deficiency of the short extensor of the thumb, or its blending with the large, approximates the formation of the hand to that of the foot.
III. TIBIALIS ANTICUS.
§ 1258. The tibialis anticus muscle, Tibio-sus-tarsien, Ch. (JVT. tibialis, s. tibiczus anticus, s. catena: musculus, s. hippicus), is the strongest of the three anterior muscles of the leg ; it arises directly at the side of the peroneus longus muscle, and is covered in this place by a broad tendon, which expands on its anterior face from the lower face of the outer part of the head of the tibia, and still lower from the outer face of this bone, nearly to its lower third, so that its fibres gradually come only from the most posterior portion, and even the inner edge of this face in all its course. At the same time it receives some which arise from the periosteum. All these fibres, which go obliquely Torward, are attached to an anterior tendon, which is loose only in a very small point of its extent downward, but which extend within the muscle even beyond its centre. This tendon, which is very strong, descends obliquely inward, passes on the anterior face of the tibio-tarsal articulation, comes upon the inner edge of the foot, where it is retained by a ligamentous band, oblique downward and backward, which extends from the scaphoid to the first cuneiform bone, and is finally attached by two short slips to the inner part of the lower face of -the large cuneiform bone, and also to the base of the metatarsal bone of the large toe.
Opposite the articulation of the foot its tendon is enveloped in a mucous sheath.
It raises the foot, turns it on its axis, so that its sole looks inward and its inner edge upward.
It corresponds to the radiales muscles of the hand.
5. Muscles of the Foot
§ 1259. The muscles of the foot arise from the tarsus and metatarsus, and are all attached to the phalanges of the toes. They are situated on the back of the foot, on its sole, on its internal and external edges. Some are common to several toes, others belong exclusively to some of them, namely to the large and small toes. The latter are only repetitions of those which are divided between several of them.
I. MUSCLES OF THE BACK OF THE FOOT.
§ 1260. Besides the tendons of the extensor digitorum communis longus and of the two peronei muscles, we find also on the back of the foot the extensor communis digitorum brevis.
EXTENSOR COMMUNIS DIGITORUM BREVIS.
§ 1261. The extensor communis digitorum brevis muscle, Calcaneosus-phalangettien commun, Ch. ( JW, . extensor digitorum pedis communis brevis, s. pediceus externus ), is a flat muscle, formed of four elongated and rounded bellies, which arises from the back of the anterior process of the calcanéum, goes forward and inward, its bellies separating from each other, and is attached -by four tendons to the four inner toes. These tendons in their course on the metatarsus cross those of the extensor communis digitorum longus, but on the toes they are situated on the outside of them. The outer three are very intimately blended, by their internal edge, with the outer edge of the tendons of the extensor longus, and consequently form their outer half ; hut the most internal, that which goes to the great toe, does not unite to the corresponding tendon of the flexor longus, but is attached below it to the posterior edge of the back of the first phalanx of the large toe.
This muscle extends the four inner toes and directs them a little outward.
§ 1262. Often and even most generally its inner belly is separated much more from the others than the latter are from each other. Very frequently it forms an entirely distinct muscle, which deserves to be noted because of the more striking resemblance established between the upper and lower extremities by this peculiarity. Sometimes the other bellies and even all are entirely detached from each other, a curious analogy with what exists in birds. Again, the extensor brevis often presents supernumerary bellies. Most commonly a small fleshy fasciculus exists between the internal and what is commonly called the second ; its tendon is attached either to the second metatarsal bone or to the tibial face of the second toe. This accessory muscle, mentioned by Albinus,(l) and which we have often seen, is curious, as it must evidently be considered as a repetition of the indicator muscle.
The second belly is also sometimes divided at its anterior extremity into two fasciculi, or sends two tendons to the second toe.
The tendons of the third and fourth bellies are often divided, so that there is for the third toe an extensor muscle or at least a tendon ; this arrangement resembles the doubling of the proper extensor of the index finger in the hand for a proper extensor of the third finger.
After this anomaly the one most frequently found consists in the presence of a small special belly for the fifth toe. We have also seen this several times, and it is interesting as an analogy either with the apes(2) or with the extensor proprius minimi digiti.
II. MUSCLES OF THE SOLE OF THE FOOT.
§ 1203. Most of the muscles of this part of the lower extremity are found in the sole of the foot.(3) In fact, besides the short head of the extensor digitorum communis already described (§ 1245), we find the flexor communis digitorum brevis, the adductor and flexor of the large and little toes, the adductor hallucis, the lumbricales, and the interossei muscles.
The adductor hallucis occupies the inner edge of the foot and that of the little toe the outer edge. A great part however of these muscles project likewise in the sole, so that it is best to study them at the same time as the other muscles of the toes, to which they belong, and to consider them as the lower muscles of the foot.
We shall describe first the common muscles, next the special muscles : first, however, their common aponeurosis.
I. PLANTAR APONEUnOSIS.
§ 1264. The plantar aponeurosis (aponeurosis plantaris) is a very firm tendinous layer, formed of longitudinal fibres, which arises from the lower face of the tuberosity of the calcanéum, directly under the skin, with which it is intimately connected. Thence it goes forward, where it enlarges very much. Arrived at the anterior edge of the metatarsus it divides into five slips, which correspond to the five toes, and which are attached to each other by transverse fibres.
This aponeurosis protects and fixes the muscles of the sole of the foot, and at the same time increases the surfaces of insertion of several.
(1) Hist, muse ., p. 602.
(2) Meckel, Beytrâge zur vergleichenden Anatomie, vol. ii. part i.
(2) A. F. Walther, Tractationes de articules , ligamentis et musculis incessu dirigendis supplemcnlvm tahulamquc novam plantœ humani pedis exhibens, Leipsic, 1731.— D. C. de Courcelles, Icônes musculorum plantœ pedis, sorumque descriptio, Au-isterdam, 1760.
II. COMMON MUSCLES OF THE SOLE OF THE FOOT.
a. Flexor dig-itorum pedis communis brevis.
§ 1265. The flexor communis digitorum brevis muscle, Calcaneosous-phalanginicn commun , Ch. (JV/. flexor digitorum pedis communis brevis , s. perforahis , s. sublimis, s. pediœus intermis ), is elongated, quadrilateral, thicker behind, and broader but thinner before. It arises by very strong tendinous fibres, which extend on a considerable portion of its lower face from the lower face of the tuberosity of the calcanéum, and by fleshy fibres by almost all its lower face, from the upper face of the plantar aponeurosis, to which its posterior tendon also adheres. Posteriorly it is very intimately united internally with the outer edge of the adductor pollicis, and above with the short head of the extensor communis digitorum longus. Nearly in the centre of the sole of the foot it divides into four very short fleshy fasciculi, which soon become as many single tendons. The latter are attached to the second, third, fourth, and fifth toes. They cover those of the extensor longus and are much smaller. They are arranged in the same manner anteriorly as those of the extensor digitorum sublimis. In fact a rhomboidal fissure begins a little before the posterior extremity of the first phalanx, which extends to before the centre of this bone. The tendons of the extensor communis digitorum profundus pass through these fissures.
The two halves of the tendon which pass through this division unite for a short extent ; then again separate, enlarge and diverge from before backward, and are separately attached by straight edges to the centre of the lower face of the second phalanx.
Each tendon of this muscle is attached with the corresponding tendon of the flexor longus, to the lower face of the toes by synovial and fibrous ligaments, exactly like those which retain the tendons of the flexor sublimis and profundus of the fingers.
This muscle flexes the first and second phalanges of the four outer toes.
§ 1266. The fourth tendon is sometimes deficient, and then it is often but not always replaced by a tendon of the flexor longus. In some subjects there seems to be an antagonism between the short extensor and the short flexor of the toes ; for we have sometimes found in this case the number of tendons of the second is greater than usual.
Sometimes also another portion of the muscle is deficient ; it is usually the most internal or the most external. It is then replaced by other fasciculi which come from the flexor of the large and that of the little toe, which reminds us of the insulation of the internal head of this muscle hi apes, and the disappearance of the short common flexor as a separate muscle in all the other mammalia and in all birds.
b. Lumbricales.
§ 1267. The lumbricales muscles, Planti-sous-phalangiens , Ch., correspond to those of the hand in number, form, and situation. They arise by fleshy fibres from the tendons of the flexor digitorum longus, and are attached, partly by short tendons, to the posterior head of the first phalanx of the four outer toes, and partly by thin tendinous expansions, to the tendons of the extensor digitorum longus.
c. Interossei.
§ 1268. We find in the foot as in the hand seven interossei muscles, Æetatarso-phalangiens latéraux , Ch. (JVf. interossei), which fill the intervals between the metatarsal bones. They arise from the posterior part and from the lateral faces of these bones, and their anterior tendons blend below with those of the extensor communis.
We distinguish them into external and internal. The first are four and the second three in number.
a. External interossei.
§ 1269. The upper and external or dorsal interossei muscles (JM. interossei externi , s. superiores, s. dorsales) are situated directly below the extensor communis digitorum brevis, in the first, second, third, and fourth interosseous spaces.
The first, which is the most internal, differs from the other three in its form and arrangement. In fact it comes only from the tibial side of the second metatarsal bone and is attached forward by a short, broad, and flat tendon to the inside of the first phalanx of the second toe.
It is however almost always divided into tw r o heads, the upper of which is longer and much thinner than the lower.
The second, third, and fourth have two heads each, which are inserted by short tendons on the outer or fibular side of the first phalanx of the second, third, and fourth toes.
The outer head is much larger, arises from the posterior part of the inner face of the metatarsal bone, which is placed directly on the outside of the toe to which the tendon is attached, and descends as deeply as the internal, on the side of the sole of the foot. The inner is the smallest, and arises from the posterior part of the outer face of the metatarsal bone of the toe in which its tendon is inserted, and descends a little lower than the preceding. The fibres of these two heads unite at a very acute angle and are implanted in a common tendon.
The first external interosseous muscle brings the first toe inward ; the second, third, and fourth carry the toes to which they are attached outward.
b. Internal interossei.
§ 1270. The internal, inferior , or plantar interossei muscles (JVf. interossei interni , s. inferiores , s. plantares) are smaller than the external and have only one head. They arise from almost all the posterior part of the inner or tibial face of the third, fourth, and fifth metatarsal bones, and are attached by a considerable tendon to the inner face of the first phalanx of the third, fourth, and fifth toes. This tendon is closely united to the capsule of the metatarso-phalangean articulation, and sends a prolongation to that of the extensor communis.
These muscles direct the third, fourth, and fifth toes inward toward the large toe.
III. PROPER MUSCLES OP THE TOES.
§ 1271. We may consider as proper muscles those of the large and small toes.
a. Muscles of the large toes, a. Abductor haltucis.
§ 1272. The abductor hallucis muscle, JWetatarso-sous-phalangien du premier orteil , Ch., is the strongest short muscle of this toe. It arises by several slips from the inside of the tarsus and the metatarsus, and is attached to the inside of the large toe. To simplify the description, we may refer these several slips to two heads.
The posterior head, which is the larger, arises by two bands, of which the inferior is longer, from the lower part of the inner side of the tuberosity of the calcanéum, and the upper, which is shorter, from the upper and projecting part of the inner face of the body of the calcanéum.
The anterior head, which is the smaller, arises by three or four distinct slips from the inner and anterior face of the astragalus, scaphoid, the first cuneiform, and first metatarsal bone. The posterior tendon of these two fasciculi covers them from their origin to near their anterior extremity below. The anterior, which is much stronger, begins near the centre of the posterior belly and is situated on its inner side ; so that the fibres of the two bellies which go forward and inward are inserted at acute angles.
This last tendon, after it disappears from the surface, extends very far within the muscle, whence it goes backward and divides into several very considerable slips. Anteriorly, it is sometimes attached by two slips to the lower and inner face of the head of the first metatarsal bone, to the inner face of the capsular ligament of the first metatarso-phalangean articulation, and principally to the inner and lower part of the base of the first phalanx of the large toe, where it adheres intimately to the flexor digitorum brevis.
This muscle brings the large toe inward and flexes it a little.
b. Flexor brevis pollicis pedis.
§ 1273. The flexor brevis pollicis pedis , Tarso-sous-phalangien du premier orteil, Ch. {JS1. flexor hallucis proprius brevis), is much shorter than the abductor. It arises behind from the tendinous sheath of the peroneus longus, intimately united to the long'head of the adductor of the large toe. Most generally its posterior extremity maybe divided into an external and an internal belly. Thence it goes inward and forward. It is attached by a short tendon, more or less divided, to the posterior part of the lower side of the base of the first phalanx of the large toe. This tendon is generally united to that of the adductor outward ; it contains anteriorly, below the two parts of the head of the first metatarsal bone, two sesamoid bones placed one at the side of the other.
This muscle flexes the first phalanx of the large toe.
c. Adductor pollicis pedis.
§ 1274. The adductor pollicis pedis muscle, Calcaneo-sous-phalangien du premier orteil , Ch. (JM. adductor hallucis), is a considerable muscle which has two bellies.
The posterior is much stronger than the other and is placed above and outside of the flexor brevis pollicis pedis. It arises from the lower side of the base of the third and fourth and also often of the second metatarsal bone, and from the sheath of the peroneus longus, above the flexor brevis pollicis pedis. Before, on its outer and lower face, are strong tendinous expansions, which unite to give rise to the anterior tendon. This latter is united to the external tendon of the flexor brevis (§ 1212), and is attached to the outer face of the base of the first metatarsal bone.
The anterior head is much smaller and weaker than the posterior, and arises from the lower and inner face of the capsular ligament, between the metatarsal bone and the first phalanx of the fourth and fifth toes, sometimes also from the anterior part of the fifth metatarsal bone.
It goes obliquely forward and inward, directly below the anterior end of the interossei muscles, between these and the tendons of the flexor communis digitorum profundus. It is attached by a thin and short tendon to that of the abductor of the great toe.
b. Muscles of the little toe.
a. Abductor minimi digit!.
§ 1275. The abductor minimi digiti muscle, Calcaneo-sous-phalangenien du petit orteil , Ch. (JVf. abductor digiti quinti), is the longer of the two muscles of this appendage, has two bellies like the abductor pollicis pedis ; the posterior belly is greater.
The posterior belly is covered below and behind by a strong aponeurosis, and arises from the posterior and from a little of the anterior part of the lower face of the tuberosity of the calcanéum.
The anterior belly comes from the lower edge of the tuberosity of the fifth toe.
Both are attached outwardly to a broad and strong tendon, which extends far back into the substance of the muscle and which is attached to the outer part of the lower face of the base of the first phalanx.
b. Flexor minimi digiti brevis.
§ 1276. The flexor minimi digiti brevis muscle, Tar so-sous-p hal angien du petit orteil , Ch. (AI. flexor digiti quinti proprius brevis), is much smaller than the preceding. It arises from the inner part of the lower side of the base of the fifth metatarsal bone and from all the lower face of its body. It may almost always be divided into an outer and inner belly. Most frequently also it is attached by two distinct tendons to the inner part of the lower side of the base of the first phalanx.
§ 1277. The muscles of the large and small toes may be referred to the other muscles of the foot, as we have seen those of the thumb and little finger could be to the other muscles of the hand. The abductor pollicis pedis is the first external interosseous muscle, and the posterior belly of the abductor the first internal interosseous muscle. The anterior belly of the latter represents the first lumbricalis. The flexor brevis digitorum pedis muscle corresponds to the flexor digitorum communis. The abductor minimi digiti is the last external interosseous muscle. Finally, the flexor minimi digiti brevis may be considered as belonging to the flexor digitorum communis, because of the slight development of the fourth tendon of the latter in most subjects.
Comparison of the Muscles of the Different Regions of the Body
§ 1278. We have already compared the muscles of the different regions of the body with each other in different directions, while describing each one particularly. They also conform to the law that the analogy betweeen the upper and lower halves of the body is more marked than that between the anterior and posterior. In fact we observe, 1st, that many muscles which succeed from above downward arc repetitions of one another, as is evident with those between the vertebrae or between these bones and the head ; 2d, the muscles of the limbs correspond very evidently, and the differences they present, like those between the bones and the ligaments, depend on the greater solidity of the lower limbs and the greater mobility of the upper, either when considered as a whole and in their relations with the trunk, or when viewed in detail and in regard to the relations of their different parts with each other. An abnormal arrangement of the muscles belonging to the two extremities frequently renders their similitude more perfect and more evident than it is generally ; and if we do not err, of all the organic systems, the muscular most frequently presents anomalies in the configuration, which cause an unusual similitude between the anterior and posterior faces of the body and also between its upper and lower portions.
In this respect we often find an anterior sternal muscle, which determines a resemblance between man and animals, and the existence of which is so curious in another respect ; and we not unfrequently find a short head of the biceps flexor cubiti and a short extensor of the middle finger.
So too the muscles of the lower limbs are frequently repetitions of those of the upper. The latter however seem to us more disposed to present assimilating anomalies in their configuration, which probably depends on a general law, amply supported by the vascular system, viz. that anomalies in the pelvic members are more frequent than in the pectoral extremities.
(1) F. Roulin, Recherches théoriques et expérimentales sur le mécanisme des mouvements et des att itudes dans l'homme ; in the Journ. de physiol. e.rp., vol. i. p. 2C9, 301,
vol. ii. p. 45, 156, 283.
General Remarks on the Motions of the Human Body
§ 1279. Having described successively the different organs of locomotion, we must now briefly examine the principal motions(l) which result from their joint action.
We must first, endeavor to prove that the erect •posture on the lower limbs is natural to man.
A. ERECT POSTURE.
I. OSSEOUS SYSTEM.
§ 1280. We may also point out in this place the conditions which arise from the other organic systems, not yet described, and which refer to the general form of the body, because the osseous system serves as the basis for all the others.
In considering the body from below upward, we discover successively in the osseous system all the conditions which render the erect posture natural to man.
1. In the lower extremities.
§ 1281. 1st. The predominance of the bones of the lower over those of the upper extremities.
2d. It is only in the erect posture that the articular surfaces of all the bones are exactly fitted to each other.
3d. The breadth of the foot.
4th. The size of the tarsus and metatarsus in proportion to the toes.
5th. The number and size of the sesamoid bones.
6th. The union of the bones of the leg with the tarsus at a right angle.
7th. The length and the obliquity of the neck of the femur.
8th. The breadth, concavity, and lowness of the iliac bones.
2. In the trunk.
§ 1282. 1st. The lowness, breadth, and curve of the sacrum, and also the curving inward of the coccyx, upon which and also on the arrangement of the iliac bones the peculiar shape of the human pelvis depends, which seems well adapted only for the erect posture.
2d. The breadth and lowness of the vertebrae.
3d. The considerable curve of the ribs, whence results the breadth and convexity of the thorax.
3. In the head.
§ 1283. 1st. The anterior, posterior, and horizontal position of the condyles and foramen magnum of the os occipitis.
2d. The direction of the cavities of the orbits and nose forward in the erect posture and downward in that on the four limbs.
4. In the upper limbs.
§ 1284. 1st. The shortness and feebleness of these members in proportion to the lower.
2d. The forced position of the bones of the fore-arm and of the radiocarpal articulation in walking on all fours,
3d. The mobility of the radius.
4th. The concavity and breadth of the bones of the metacarpus and of the phalanges. These latter circumstances indicate that the bones of the upper extremities are intended to grasp external objects, while the corresponding parts of the lower limbs prove they are designed to support the body.
II. LIGAMENTOUS SYSTEM.
§ 1285. The peculiarities of the ligamentous system are as follow :
1st. The ligaments of the lower extremities are stronger than those of the upper, and this strength increases progressively from below upward.
2d. The looseness of the cervical ligament, although the head is very much developed, in regard to the occipital foramen which is situated farther forward.
III. MUSCULAR SYSTEM.
, § 1286. The muscular system also furnishes several strong argu ments :
1st. The greater power of the muscles of the lower extremities.
2d. The extreme force and the arrangement of some of them, viz.
a. The thickness of the peronei muscles in the leg, the lower head of which always draws the leg backward arid extends it, whiie the upper two prevent the body from falling forward.
b. The arrangement of the flexors of the leg compared with that of the flexors of the fore-arm ; for one of the three long flexors of the first of these limbs is manifestly developed only in part ; so that the number of the corresponding muscles in the fore-arm is much greater than in the leg.
c. The thickness of the glutæi muscles, particularly the glutæus maximus.
d. The multiplication of the muscles of the fore-arm to execute the peculiar motions of the bones of the fore-arm : so likewise the difference between the number and development of the special muscles of the thumb and little finger and those of the large and small toes.
e. The deeper situation of several of the muscles' of the fore-arm in the upper extremity, and the foot only in the lower : such are particularly the flexor brevis and the extensor communis brevis.
f. The slight extent of the insertion of the flexors of the leg, which favors the extension of this limb and prevents the continued forced flexion it experiences in quadrupeds.
g. The smallness of the small muscles of the head, which, in connection with the looseness of the cervical ligament and the anterior position of the occipital foramen, forms a very striking character, especially when we regard the great development of these parts in quadruped the head of which is however smaller than that of man.
§ 1287. All these circumstances united prove sufficiently that the erect posture on the lower limbs is natural to man.
We must next examine how the erect posture is preserved in a state of repose, and how the body when erect exercises the motion of progression, or of standing and of â– walking, treating of the modifications of each.
B. OF STANDING.
§ 1288. The trunk and the lower limbs act in standing. The part taken by the trunk consists,
1st. In the support of the head by the vertebral column.
2d. In the action of the very strong long muscles of the back which fill the channels between the vertebrae and the ribs. They prevent the body from falling forward, to which it is in some measure disposed from the portion of the pectoral and abdominal viscera before the vertebral column. In fact, they are much more developed in their lower part than at their summit. In this part also we feel fatigue and pain most sensibly after standing a long time and especially after leaning forward.
Tire trunk is supported by the lower extremities. Whenever the position changes the pelvis presents a broad point of support for its weight, and that of the head which is sustained by the vertebral column. The articulation of the ossa femoris with the iliac bones in front of their union with the spine increases the extent of this base of support.
In standing, the weight of the body passes from this base to the thigh, next to the leg, and finally to the foot, so that the body rests upon the latter.
In the usual p ition on the two feet, besides the peculiarities relative to the lower ex. . amities and which we have mentioned above, their separation caused by the breadth of the pelvis and the length of the neck of the thigh bones is very advantageous, as it increases the extent of the base of support which falls between the soles of the feet ; thus the attitude becomes unsteady and less firm when the breadth is diminished by approximating the feet.
Standing, inasmuch as it depends on the lower limbs, results’ from the action of all the muscles which arise from the trunk, and from the different sections of these members. These muscles contract from above downward, and thus move the divisions immediately above them, and act in a direction the inverse of that which results in progression, since they approximate the least movable point to that which is most movable. Thus the most active are, 1st, the gliitæi, which draw the trunk backward ; 2d, the three flexors of the leg, which prevent the pelvis from inclining forward ; 3d, the extensors of the thigh, excepting the rectus, which prevent the limb from falling backward ; 4th, the lower head of the triceps, suree, which keeps the leg on the foot in a direction intermediate between flexion and extension.
The other muscles, which confine the action of those we have mentioned, have little or no action, and this action is counteracted by that of the others.
Standing on one foot, where the whole weight of the body rests on one of the lower extremities, is practicable, especially by the length of the neck of the femur and the breadth of the sole of the foot. This posture of the body is preserved by the action of the muscles on the outside of the lower limbs, by the broad abdominal muscles, and by the quadratus lumborum, which act from below upward, preventing the body from falling to the opposite side, where it is unsupported.
In standing on the toes there is no change except in the relations of the bones of the leg and the action of its muscles. The toes are extended as much as possible on the metatarsal bones and the foot on the leg, and the weight of the body then rests wholly on the toes and also on the sesamoid bones of the foot, which are numerous and large. This position is caused principally by the simultaneous action of the muscles situated on the anterior and posterior faces of the leg and foot ; the tibialis anticus, the peronei, especially the peroneus brevis, the extensors of the toes anteriorly, and the triceps suræ posteriorly, are the principal agents.
At the same time the toes are forcibly pressed against the ground by the action of their flexors, hence they are - more firmly fixed and afford a more solid point of attachment to their muscles.
C. OF WALKING.
§ 1289. Walking is produced by the displacement of the lower extremities, which move alternately either forward, backward, or laterally, so that a distance exists between them, and consequently the rest of the body is supported by only one of them. Each motion, by which a limb is raised from the ground, separated from the other, and is replaced on the ground, is a step.
This motion, in whatever direction it is performed, depends principally on the displacement of the femoral articulation, which is flexed in walking forward or sideways, and, on the contrary, extended in walking backward.
When we walk forward or backward the knee-joint is generally slightly bent, which serves to raise the foot still more. The metatarsophalangean joint is most generally forcibly extended, articular when the lower limb which is to be moved is behind the other; In walking, the flexion of the haunch carries one of the two limbs more or less before the other ; when left to itself, and the coxo-femoral articulation is not bent, the foot falls again to the ground and the step is finished. If we take long steps the pelvis also turns more or less around the limb which remains fixed as around an axis ; hence the limb which moves, and the corresponding side of the body, are carried farther forward. This effect is caused partly by the flexion of the other sections of this limb and partly by the extension of the metatarso-phalangean articulation.
It is merely necessary to mention these motions to know the muscles which perform them.
Running is a quick walk, most generally withlarge steps, which
differs from the ordinary walk not only by its rapidity, but also because
all the lower face of the foot rests on the ground.
Jumping is a sudden movement by which the body rises into the air. In order to perform it all the joints of the lower limbs are flexed and then suddenly extended ; from the shock which the body experiences from the soil against which it strikes it is carried upward until its weight exceeds the motion communicated to it, and causes it to return to the earth.
The leap in a straight line is always shorter than the oblique leap because the weight of the body presents more resistance in the first case than in the second.
In kneeling the articulation of the foot is flexed by the anterior muscles of the leg, which act from above downward, and the articulation of the knee is changed in the same manner by the action of the upper heads of the triceps suræ muscle.
In stooping the gastrocnemii muscles of the leg exercise all their power ; at the same time the coxo-femoral articulation is flexed more or less forcibly in order to lean the body forward, and to prevent its centre of gravity from falling behind its base of support, and in this manner to prevent its fall.
§ 1290. The motions of the trunk{ 1) are very limited. This is proved by the vertebrae and also by the pieces of the sternum, which are firmly united. Thus the motions of the trunk in every direction depend but slightly on the displacement of the bones which form it, but almost entirely on the lower limbs, and those in the coxo-femoral articulation, are performed by the muscles which extend from the thigh and leg to the vertebral column and to the iliac bones. The mobility of the ribs is much greater ; the changes in their situation produce the continual alternate changes which take place in the capacity of the chest, and which result in inspiration and expiration. The examination of these changes and of those which occur in the capacity of the abdominal cavity will be more in place after describing the pectoral and abdominal viscera than here.
§ 1291. The head moves on the vertebral column ; it bends forward, is extended backward, inclines to the side, and turns on its axis.
The last two motions take place almost entirely between the second and first vertebræ, the last of which only accompanies the head. The other two occur between the head and the atlas, and not between the atlas and axis, because the odontoid process and the transverse portion of the crucial ligament almost entirely prevent every displacement in this direction between the first and second vertebræ.
Luxation cannot take place in flexion and extension on account of the firmness of the attachments ; but it easily supervenes in the rotation of the first vertebra and of the head on the axis, when this motion is performed quickly.
(1) Winslow, Sur les mouvemens de la tête, du cou et du reste de l’épine du dos , in the
Mém. de Paris, 1730, p. 492-503.
The cervical portion of the vertebral column must always be fixed
in order that these different motions ma_y be executed.
§ 1292. The b upper limbs are much more movable than the lower both in regard to the trunk and their different sections, which doubtless depends on the arrangement of these bones and the ligaments. The motion of rotation on the axis particularly is much easier in the first than in the second. The greater mobility of the upper limbs, considered as a whole, is also increased by the difference remarked in the mode of articulation, of the first section of the bones of the two extremities, for the iliac bones are almost motionless on each other and on the vertebral column, while the clavicle and scapula on the contrary are very movable both on each other, and on the trunk.
Hence the motions of the upper limbs are not performed solely in the scapulo humeral joint as those of the lower extremities are in the coxo-femoral articulation, but take place at the same time in the scapulo- and sterno-clavicular articulations ; hence they are not only more free, but also keep the bones together in the different motions they perform. Hence the bones are much less firm, but they require less strength, since the upper extremities are rarely obliged to sustain such heavy loads as happens for instance in creeping, walking, or standing on the hands.
If we except the fingers and toes, mobility diminishes from the periphery of the limbs to their centres.
A great difference between the partial motions of the two limbs consists in the power of turning the radius on its axis and around the ulna while the leg cannot move around the thigh, except as a whole, the fibula being immovable on the tibia. The leg is capable only of flexion and extension, while the fore-arm can execute also the motions of pronation and of supination.Q I.)
Although in the two latter motions the radius is the principal part displaced, the ulna is not however motionless ; for it is slightly extended in pronation and a little flexed in supination.
(1) Winslow, Obs. anat. svr la rotation , la pronatiop, la supination et d'antres moiivcmens en rond, in the Mérn. de Paris, ÎV27, p. 25-33, — Vicq ci’Azyr, Œuvres, vol. V. p. 343-351.
Book IV. Angiology
§ 1293. The vascular system(l) is composed of a central part, the heart , whence all the blood departs and where all this fluid returns ; of vessels which carry it away, the arteries ; and of vessels which
(1) We have already mentioned (vol, i. p. 280) the most important works on the general conditions of the structure and external form of the vascular system in the normal and abnormal state. We shall now mention the principal descriptive treatises. They are,
I. Foe the whole system. — J. C. A. Mayer, Anatomische Beschreibung der Blutgefässe des menschlichen Körpers , Berlin, 1777, 1778. — F. A. Walter, Angiologisckes Handbuch, Berlin, 1789.
II. Foe the heart, — 1st. Complete description of this organ in all its parts, both in the normal and the abnormal state ; Senac, Traité de la structure du cœur, de son action et de ses maladies, Paris, 1747, 1778. — 2d. Complete description of it in the normal state ; R. Lower, Tractatus de corde, item de motu calore et transfusione sanguinis, London, 1669. — J. N. Pechlin, De fabrica et usu cordis, Kiel, 1676. — Winslow, Sur les fibres du cœur et sur ses valvules, avec la manière de le préparer pour le démontrer, in the Mémoires de Paris, 1711, p. 196, 201.— Vieussens, Traité de la structure et des causes du mouvement natural du cœur, Toulouse, 1711. — Santorini, Obs. anat ., Venice, 1724, ch. viii., Deiis quee in thoracemsunt . — Lieutaud, Obs. anat. sur le cœur, in the Mém. de Paris, 1752, 1754. — 3d. Development of the heart; Meckel, Sur l'histoire du développment du cœur et des poumons dans les mammifères, in the journal complém. du Diet, des sc. médic., vol. i. p. 259. — Rolando, Sur la formation du cœur et des vaisseaux artériels , veineux et capillaires, same journal, vol. xv. p. 323, vol. 16. p. 34. — Prévost et Dumas, Développment du cœur et formation du sang, in the Annales des sciences naturelles, vol. iii. p. 46. — 4th. Structure of the heart in respect to. the arrangement of its fibres ; C. F. Wolff, Dissertationes de ordine fibrarum muscularium cordis, in the Act. Acad. Petropol., 1780-1781, in the Nova act., vol. L-viii. — J. F. Vaust, Recherches sur la structure et les mouvemens du cœur, Liege, 1821. — S. N. Gerdy, Mémoire sur l'organisation du cœur, in the Journ. compl. du Diet, des sc. méd., vol. x. p. 97. — 5th. Pathological state ; A Burns, Observations on some of the most frequent and important diseases of the heart, London, 1809. — Pelletan, Mémoires sur quelques maladies et vices de conformation du cœur, in the Clinique chirurgicale, Paris, 1810, vol. iii. — Testa, Delle malattie del cuore, loro cagioni, specie, cura, Bologna, 1810, 1813.' — Corvisart, Essai sur les maladies et les lésions organiques du cœur et des gros vaisseaux, Paris, 1818. — Kreysig, Ucber die Herzkrankheiten, Berlin, 1814, 1817. — Laennec, De l'auscultation médiate , or Traité du diagnostic des maladies des poumons et du cœur, Paris, 1819, p. 195-445. — Bertin, Traité des maladies du cœur et des gros vaisscu. v, Paris, 1824.
III. For the arteries. — H aller, Icônes anatomicœ, Gottingen, 1745, 1756. — A. Murray, Descriptio arteriarum corp. humani tabulis redacta, Upsal, 1783, 1798. — J. F. S. Posewitz, Physiologie der Pulsadern des menschlichen Körpers, Leipsic, 1795. — J. Barclay, A description of the arteries of the human body, Edinburgh, 1818, 8vo. — Tiedmann, Tabulae arteriarum corporis humani, Carlsruhe, 1822, 1824. — Hodgson, Diseases of the arteries and veins.
IV. For the veins. — B esides the tables of Loder see Breschet, Sur le système veineux, now publishing.
V. For the Lymphatics. — T he works mentioned in the first volume contain also a description of this system.
184
DESCRIPTIVE ANATOMY.
return it, the veins and the lymphatics. The last mentioned carry a
fluid different from the blood, they are the annexes or appendages of
the venous system.
SECTION I.
OF THE HEART.
CHAPTER I.
GENERAL REMARKS.
§ 1294. The heart (cor) is a hollow muscle irregularly conical or pyramidal, situated in the centre of the chest, between the two lungs, and inclosed in a special envelop called the pericardium. Its vessels are numerous, but it has few nerves : it is formed of several cavities, some of which are separated, while others communicate together. Its tissue is formed of fibres united in superimposed layers, and is connected on one side with the large venous trunks of the lungs and body, and on the other with the large arterial trunks of both. Each of these characters deserves to be specially considered.
I. FORM.
§ 1295. The shape of the heart is that of a cone or an irregular pyramid. We distinguish in it a broad and thick base (basis) and a summit (apex), which is generally blunt and bifurcated, an upper and anterior face which is concave, and an inferior and posterior which is smaller and flatter ; two edges, a posterior which is thick and pointed, the anterior is smaller, shorter, thin, and sharp.
The base of the heart is formed, properly speaking, by that part of the organ directly connected with the veins : we may then term it the venous portion of the heart (pars cordis venosa). However we generally apply the term base of the heart to the upper region of the arterial portion. The venous portion is formed of two auricles. It is separated from the next by a large groove, called the groove of the base , the auricuto-ventricular groove , or circular groove ( sulcus baseos , s. alrio-ventricularis, s. circularis). Its form is an oblong square and its breadth exceeds its height.
The succeding portion, which is situated before the auriculo-ventricular groove, is directly connected with the large arterial trunks. We may then term it the arterial portion of the heart (pars arteriosa cordis). It is formed by the two ventricles. It terminates in a blunt summit, which is usually more or less evidently grooved. This groove is sometimes very large.
ANGEIOLOGY.
185
The longitudinal groove (sulcus cordis longitudinales superior et inferior) exists on both faces of the heart, from its base to its summit, and
consequently in all its length.
The principal branches of the nutricious vessels of the organ are situated in these grooves : they communicate on the side of the base by a groove, which descends perpendicularly between the two auricles, and on the summit by the depression observed in this place. They mark the course of the septum within the heart (septum cordis).
§ 1396. The septum passes also across the venous portion of the heart or the auricles as well as its arterial portion or the ventricles. It separates completely these two synonymous parts, and consequently divides the heart into a right or an anterior and a posterior or left half. That part which passes between the auricles is called the septum atriorum, and that between the ventricles is called the septum ventricidorum. The right part of the heart is called the pulmonary heart (cor pulmonale), because the pulmonary artery arises from it, or the heart of the black blood, from the color of this fluid within it. The left is termed the aortal heart (cor aorticum ), because the aorta arises from it, or the heart of red blood, from the color of the blood within it. We employ sometimes also the terms of first ventricle, to designate the anterior, and second ventricle, to mark the posterior ; but these are less convenient.
II. WEIGHT AND SIZE.
§ 1297. The weight of the heart in a fully grown man is about ten ounces ; whence it is to that of the whole body as 1 is to 200.
Its length, measured from the centre of the auricles, is between five and six inches its mean length is five and a half inches, four of which are for the ventricles and one and a half for the auricles. The breadth of the ventricles united is generally three inches at their base and that of the auricles is three and a half inches. (1 )
III. SITUATION.
§ 1298. The heart is placed obliquely from right to left, from behind forward, and from above downward ; so that its base is nearly opposite
(1) A knowledge of the perfectly normal proportions of the heart in the healthy state is very important to the physician, since without it he can establish no certain diagnosis of the diseases of the central organ of the circulation. We cannot do better than to quote the following passage of Laennec on this subject : “ The heart, in cluding the auricles, should be equal to, a little less, or a little larger than the first of the subject. The walls of the left ventricle should be a little more than twice as thick as the walls of the right ventricle ; they should not collapse on cutting into the ventricle. The right ventricle, a little larger than the left, presenting- smaller fleshy pillars, although its parietes are thinner, ought to collapse after the incision.†(De V auscultation médiate, vol. ii. p. 270.) “Reason teaches and observation proves, that in a well formed subject the ca\ ities of the heart are nearly equal ; butas the parietes of the auricles are very thin and those of the ventricles are much thicker, it follows that the auricles form only one third of the whole volume of the organ or the half of that of the ventricles.†( lb .) ~ F. T.
VOL. II.
24
1S6
DESCRIPTIVE ANATOMY.
the eighth dorsal vertebra, from which it is separated by the esophagus and aorta, and its summit corresponds to the cartilage of the sixth
rib, or to the interval, which separates it from the next. Its lower face,
which is flattened, corresponds to the upper face of the central tendon
of the diaphragm, and the upper to the central and left portion of the
anterior wall of the chest.
IV. TEXTURE.
§ 1299. The heart is formed of several layers of muscular fibres, situated between two thin, smooth, and polished membranes, the inner and outer membranes of the heart. The latter is the inner layer of the pericardium.
The outer surface of the heart is smooth and uniform in relation to the inner, even when we have removed the outer membrane.
The inner surface is very uneven and reticulated, which arises from its being formed of numerous rounded, flat, and distinct muscles, which intercross continually and which are called fleshy •pillars ( trabeculœ carneœ). The mnscular substance of the heart is generally harder, more solid, and more elastic than that of other muscles.
As the arrangement of these fibres(l) differs wholly in the venous portion from what it is in the arterial portion, as it is not exactly the same in the right and left portions, and as it finally differs according to the subject, all that can be said generally may be reduced to the following corollaries :(2)
1st. The directions of the layers are more or less opposite. But in the recent state, far from being entirely separated from each other, they intercross differently ; so that all those of one portion of the heart constantly contract uniformly and diminish the cavity they circumscribe in every direction.
The union of the different layers takes place partly by more or less manifest muscular fibres.
2d. The fibres which form the layers are united in fasciculi of various sizes, which vary more or less in their origin and their direction, and which are often separated by greater or less spaces. These fasciculi are sometimes rounded and sometimes flattened, — a difference which seems to depend on determinate laws, since it is constant in the different regions of the heart. For instance the right and left ventricles
(1) Wolff, De online fibrarum muscularium cordis, diss. vii. De stratis fibrarum in Universum. In nov. act. petrop., vol. iii., 1785, p. 227-249. — Gerdy, loc. cit., p. 101. — Vaust, loc. cit., p. 102, etc.
(2) Gerdy has established a law, that all the fibres, whatever is their extent, situa tion, and direction, form webs, which are convex toward the point of the heart, and which are nearly superficial at one extremity and deep at the other ; so that for instance the external or internal fibres are the same reversed, and having passed through the thickness of the ventricle. The extremities of these muscular webs are constantly inserted in the base of the heart, around the different auricular'and arterial orifices of the ventricles, either directly or by tendons attached to the auriculoventricular valves (loc. cit., p. 101). F. T.
ANGEIOLOGY.
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are not similar in this respect nor in regard to the arrangement of their
fibres, and the same is true of other parts also. Thus the inner layers
are generally rounded and form fleshy pillars. The auricular appendages of the auricles are formed of rounded fasciculi, and the auricles of
flattened fasciculi.
From this arrangement we may deduce that the firmest parts are formed of rounded fasciculi. But the fibres and the fasciculi formed by them are united by intermediate fibres, which may be distinguished with facility.
The fibres and fasciculi are every wdrere interlaced with each other, conformably withall the in voluntary muscles. They are united principally in two ways : sometimes the ends of the fibres and fasciculi join, and sometimes they are united by intermediate filaments, which arise from their lateral portions.
In the first case, either the fasciculi go to meet each other and the extremities of those which continue together intermix like the teeth of a saw, as is the case with the digitations of several adjacent muscles, or some fibres are attached obliquely to others at acute angles, as the fibres of the penniform muscles are implanted in their tendons, and finally, as is the case most generally, the fibres or fasciculi which go side by side unite at very acute angles.
The lateral union takes place principally between the insulated fibres and the small fasciculi of fibres, especially in the outer layer. Sometimes it is irregular ; so that those fibres which are evidently separated in the rest of their course are placed one against another in a part of this same course, whence the reticulated structure is more or less evident. It is sometimes regular, and we see oblique fibres going from each side, which unite. The redness and determinate form of the intermediate filaments always demonstrate that they are not formed of cellular tissue but of real muscular substance.
The mode in which the filaments are united also presents determinate differences in the different regions of the heart.
3d. In the ventricles, the external layers go obliquely downward, backward, and from right to left. The direction of the central is opposite, and the most internal, which form the fleshy pillars, extend longitudinally from the summit to the base.
On the contrary, the transverse direction predominates in the auricles. The external layer, which is the strongest, proceeds in this direction, while the internal, which forms only insulated fasciculi, has a longitudinal direction.
4th. All the external layers are not equally extended. Generally the external layers are those only which cover all the surface of the ventricles ; the central are smaller and occupy only a third of the heart. If we except the most internal, that which forms the fleshy pillars, they diminish in direct ratio to their depth. They disappear first at the summit of the organ, and in reascending from this point to the base of the ventricles, they are deeper and deeper ; so that the deepest
ISS
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arc found only at the base. Hence this part of the heart is the
thickest.
We observe also occasional spaces between the layers, which extend the whole length or all the breadth of the ventricles.
5th. The outer layers differ from the central ones, inasmuch as they are stronger and their fibres are more intimately united together.
Thus the fibres and the fasciculi of the inner layers are more easily demonstrated. But the external forcibly embrace and compress these latter ; so that they contribute essentially to the firmness of the heart.
6th. The fibres of the two portions of the heart are not continuous, at least not all of them, with each other, so that the same layers are reflected on the two ; but the fibres of the two ventricles terminate in the septum. The upper and lower faces of the heart are not arranged in precisely the same manner : the separation is seen with more difficulty in the first than in the second. We remark also three different arrangements in the upper face. In fact, either we cannot distinguish the least trace of separation and the fibres are uninteruptedly continuous with each other, or two fibres are in fact applied one on the other, but a species of suture serves as a line of demarkation between them, or finally they mingle with each other by digitations.
Wolff states that on the lower face, the fibres of the two ventricles are separated by a distinct and very broad band, formed of longitudinal fibres, and which diminishes insensibly from the base to the summit, to which these fibres are attached on the two sides. But we have usually found but a slight, and often no trace of this arrangement.
7th. The upper extremities of the fibres of the heart are attached to a fibro-cartilaginous tissue,(l) formed
a. Of two oblong, rounded projections or tubercles, usually three or four lines long, little less than a line thick, seen on both sides of the orifice of the aorta.
b. Of a thin band, which surrounds the posterior part of the circumference of the aorta and unites the two tubercles.
c. Of four filaments, placed in the circular groove on the base of the heart, two on the right and two on the left, an anterior and posterior on each side. Below these four filaments the two anterior arise from the tubercles. The right anterior goes into the anterior and upper part of the circular groove ; the left into the upper and posterior part. The posterior two arise by a very short common trunk, which is only a few lines long, from the band which unites the two tubercles, near that of the right side, and proceed in an opposite direction to the lower part of the circumference of the circular groove.
These anterior and posterior filaments are situated at the venous orifices of the ventricles. They do not surround the base of the heart
(1) C. D. F. Wolff, Dc or dine fibr arum muscularium cordis , Diss. ii., de textu cartilagine ocordis , sivc dcfilis cartilagineo-osseis corumque in basi cordis distribution. In Act. Petropol., 1781, vol. i. p. 211. — Gerdy, loc. cit., du tissu albugine cardiaque , p. 97.
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and form a complete ring, but terminate near the edges of each orifice
and gradually lose themselves in the cellular tis'sue.
This cartilaginous tissue is surrounded entirely by a thin, firm, but loose sheath, a real perichondrium. It is covered more externally by the outer membrane of the heart and internally by its inner membrane.
The external muscular or superficial fibres arise principally from the cartilaginous tubercles and filaments, and from the cellular tissue between the extremities of the latter ; so that the fibres, which come from the tubercles and from the origin of the filaments, adhere to them very intimately, while the others are united only by a cellular sheath which surrounds them.
v. vessels. (1)
§ 1300. The blood-vessels of the heart are proportionally very large and are called the coronary vessels ( vasa coronaria cordis). The coronary arteries and veins resemble each other in many respects :
1st. These vessels (the arteries) arise directly from the beginning of the trunks of the vessels of the body, or they (the veins) open directly into the heart.
2d. They turn around the base of the heart in the circular groove, whence they send toward the summit large branches which arise at almost right angles : these go to the ventricles and proceed along the heart, while the others are smaller and follow an opposite direction, proceeding to the auricles.
3d. The large trunks and the large branches extend on the outer face of the organ and ramify internally.
4th. The veins have valves at the places where they open but not in their course. There are two arteries of nearly equal calibers, while we find only a single large coronary vein, which is constant ; but beside this last we observe several, which are smaller, which open 'directly into the heart, but not constantly, except into the right part of the organ, and particularly into the right auricle : they do not open, even, except into the septum, and they do not empty their blood into the left part of the heart, (2) as some anatomists have pretended, and among others Vieussens(3) and Thebesius.(4) In fact, Abernethy has very recently supported this latter opinion, viz. that the venous blood of the heart mixes with the arterial blood which nourishes the body, without passing through the lungs ; he has only modified it by saying, that these orifices of the coronary veins in the left portion of the organ serve principally to prevent repletion of the right portion in those cases where the passage of the blood through the lungs is obstructed ; because,
(1) Haller, De vasis cordis propriis, Gottingen. 1737. — Iterates observationes, 1739. — Geisler, Commentatio de sanguinis per vasa coronaria cordimotu, Leipsic, 1743.
(2) Sabatier, Sur les veines de Thebesius ; in the Traité d’anat., vol. iii.
(3) Nouvelles découvertes sur le cœur, Montpelier, 1706. — Traité du cœur, 1715.
(4) De circula sanguinis in corde, Leipsic, 1708. — De circulo sanguinis per cor , Leipsic, 1759.
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having injected the cardiac arteries and veins in a subject whose lungs
were diseased, he has seen the fluid penetrate into the left ventricle by
broad openings. But as generally injections, even when very fine,
transude on all the inner face, although no venous orifices are perceptible on the left side, we have reason to admit that the openings existing in the cases observed by Abernethy were produced accidentally,
either during life or after death, by obstacles to the course of the injection, on account of the feeble resistance of the tunics of the veins weakened by disease, and considerably distended, both by the blood accumulated in these vessels and by the injected mass.
VI. NERVES.
§ 1301. The nerves(l) of the heart are proportionally smaller than those of the voluntary muscles. They arise from the upper and lower cervical ganglions of the great sympathetic nerve, from the cervical portion of the nerve between these two ganglions, or from the central ganglion sometimes found in this place. Some arise directly from the nerve, others from the plexuses formed by the filaments which come from the ganglions and by others sent off by the pneumo- gastric nerve.
The relations of the nerves of the heart with its muscular substance have been the subjects of dispute. Some anatomists, Behrends(2) among others, deny that this substance, and consequently that the heart, possesses nerves, which they pretend are distributed only to the cardiac vessels. Others on the contrary, as Scarpa, Munniks,(3) and Zeirenner,(4) maintain that they really go to the heart as well as to all other muscles.
The partisans of the first hypothesis adduce the following arguments :
1st. Anatomical examination, whence it results that the cardiac nerves, which we cannot follow except to the third ramification of the coronary arteries, do not enter the substance of the heart but go only to the arteries. (5)
2d. The origin of the cardiac nerves ; they arise from the great sympathetic nerve, the ramifications of which go only to the arteries. (6)
(1) J. F.. Neubauer, Descriptif) nervorum cardiacorum, Frankfort and Leipsic,
1772. He has figured the nerves of the right side. — E. P. Andersch, De nervis ; in the
Nov. comm. Gœtt ., vol. ii., and Königsberg, 1797. He has represented those of the left
side. These figures have been copied in Haase, Cerebri nervorumque corporis humant
repetita, Leipsic, 1781. — A. Scarpa, Tabulœ neurologicæ ad illuslrandum historiam
anatomicam cardiacorum nervorum cerebri , glossopharyngœi et pharyngæi ex octavo
cerebri, Pavia, 1794.
(2) J. Behrends, Diss. qua demonstratur cor nervis carere, additâ disquisitione de vi nervorum arteriös cingentium, Mayence, 1792.— A. T. N. Zerrenner, An cor nervis careat iisque carere possit? Erford, 1794.
(3) Observationes varice. Diss. auat. med., Groningue, 1805, 1-17.
(4) Zerrenner, An cor nervis careat iisque carere possit ? Erford, 1794.
(5) Behrends, loc. cit , p. 5, 8.
(6) Id., ibid., p. 8.
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191
3d. The smallness of those nerves which is in direct ratio with the
thinness of the fibrous coat of the arteries,(l) and which contrasts on
the contrary with this law, that the number and size of the nerves
correspond to the power and frequency of the motions of the muscles.^)
4 th. The insensibility of the heart, the motions of which are independent of the nervous system, since it beats regularly although removed from the body, (3) and the excitement of the nerves, whether mechanically or dynamically, by means of galvanic electricity, do not alter its motions, (4) and its pulsations are not deranged when the nervous system is paralyzed as in apoplexy. (5)
5th. The integrity of the motions of the heart, notwithstanding the administration of opium. (6)
But all these arguments can be refuted with greater or less facili'y. In fact :
1st. The manner in which the cardiac nerves are distributed and their proportion both to the muscular substance and to the vessels, do not differ essentially from what is seen in the same respects in the voluntary muscles. (7) Here also the nerves and the ramifications of the vessels are very compactly situated in regard to each other, and we do not see the nerves unite to the muscular substance. Besides the cardiac nerves are closely connected with the vessels only in their largest branches, and not at all in many animals.
2d. The muscular substance of the heart is only a greater development of the fibrous membrane of the vascular system, so that the distribution of the branches of the great sympathetic nerve within it does not present an aberration from the type of this nerve.
3d. The cardiac nerves possess more medullary substance than those of the voluntary muscles. They arise from the ganglions of the great sympathetic nerve, and through them from ail the _ spinal marrow. Their action is probably favored by the mutual contact of the blood and of the inner face of the heart ; very probably also the size of the nerves which go to the voluntary muscles relates to their functions which is to conduct the influence of the will.
4th. The facts cited in the fourth paragraph are explained partly by the smallness and partly by the texture especially the softness and gelatinous nature of the cardiac nerves, and from the circumstance that they arise from the ganglions. Besides they are correct only to a certain extent, since the motions of the heart are not entirely independent of the nervous system. The passions have a marked influence on the number and strength of its pulsations. Impressions of
(1) Behrcnds, loc. cit., p. 8, 9.
(2) Id., ibid., p. 10.
(3) Id., ibid., p. 11.
(4) Id., ibid., p. 20.
(5) Id., ibid., p. 12.
(6) Id., ibid., p. 11.
(7) Scarpa, loc. cit., § 13. — Munniks, loc. cit., p. 6.
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DESCRIPTIVE ANATOMY.
every kind on the nervous system modify its motions more or less sensibly.(l)
In fact several observers, particularly Valli, Volta, Klein, (2) and Bichat, have doubted the influence of electricity on the motions of the heart; but the observations of Fowler, Schmuck, Pfaff,(3) Rossi, (4) Giulio,(5) Humboldt, (6) Munniks,(7) and Nysten, and our own also, prove it to be real.
The non-affection of the heart in paralysis of the brain proves nothing' in regard to the relations between the nerves and this organ, since the irritability of the voluntary muscles is not altered in apoplexy. This apparent difference depends only on that between the excitants of the voluntary and involuntary muscles. In fact the excitant of the first is the influence of the brain, and that of the second the substance contained in their cavity, which in the present case is the blood. The motions of the heart continue also in cerebral paralysis, while those of the other muscles are not performed ; the activity of these last seems extinct while it is only no longer seen.
5th. The observations of Haller, of Fontana, of Whytt,(8) and of Alexander, (9) prove that the heart, like the voluntary muscles, is sensible to the influence of opium, whether the narcotic acts directly upon it, or is placed in contact with the nervous system or with any organ whatever. These observations and experiments prove that the relation between the heart and the nerves is perfectly like that between the nerves and muscles generally, and more, because the effect of opium upon the heart is much more evident when this substance is placed in relation with the nervous substance than when applied directly to the heart.
VII. VENOUS PORTION.
§ 1302. The characters of the venous for lion of the heart, (10) the auricles, are,
1st. The muscular substance of its parietes is so thin that the two membranes of the heart touch in several places.
2d. Its form is irregularly quadrilateral.
(1) See on this subject Legallois, Experiences sur le principe de la vie, Paris, 1812, . — Wilson Philip, in the Phil. Trans ., 1815, part i. p. 65-97 ; part ii. p. 224-246. — Ici. An experimental inquiry into the laws of the vital functions, London, 1818.
(2) In Pfaflf, Vcber thicrischc Electricitât und Reizbarkeit, p. 119.
(3) In PfaflF, loc. cit., p. 140.
(4) Mém. de Turin , vol. vi.
(5) Voig’ht, Magazin , vol. v. p. 161.
(6) Ueber die gereizte Muskel-und Nervenfaser , vol. i. p. 340-349.
(7) Loc. cit., p. 115.
(8) In Pfaffj loc. cit., p. 140.
(9) Memoirs of the Manchester society, vol. i. p. 98.
(10) Ruysch, Epist. anat. problemala décima de auricularum. cordis earumque fibrarum molricium structura, Amsterdam, 1725. — A. F. Walther, De structura cordis auricularum, Leipsic.
ANGEIOLOGY.
193
3d. It is composed of a part into which the veins open directly the
cavity of the auricle , the sac (sinus), and another upper and anterior,
the auricular appendix (auricula), which projects above the sac.
The exact limits of these two parts cannot be pointed out, or rather anatomists do not distinguish them according to the same principles on the right and left sides. On the left side the appendix is readily distinguished from the sac, because it suddenly forms a very rounded projection, which is much narrower, and has thicker walls on the upper anteiior and left angle. On the right side, on the contrary, this name is applied to a part, the walls of which are very thick, which is formed on the left by the confluence of the two venæ eavæ, terminates above in a blunt summit, and which is not sensibly separated from the rest, while, if we remained true to the analogy, this term should be applied only to the small appendix which terminates the auricle above, and which is elevated on the left along the vena cava superior.
4th. It is directly continuous with the venous trunks which open into it.
VIII. ARTERIAL PORTION.
§ 1302. The characters of the arterial portion of the heart, the 'ventricles, are,
1st. Their parietes are thicker, so that the internal and the external membranes are every where separated from each other by a muscular substance. The thickness of the parietes of each portion of the heart is then in direct ratio with the extent passed through by the blood it sends forward.
2d. The arterial portion is considerably larger and broader than the venous portion.
3d. Its external form is elongated, rounded, and pyramidal, and determines, properly speaking, the form of the whole heart.
4 th. At its upper extremity are two openings, the venous and the arterial, which establish the communication, the first between the ventricle and the auricle, and the second between the ventricle and the artery w hich arises from it. The venous orifice is almost perpendicular ; its direction is from before backward and from right to left ; the arterial is almost horizontal and is situated a little above the former farther inward and nearer the septum.
Both are rounded j the venous is broader than the arterial. Its form is elliptical, while the latter is nearly circular.
Neither the venous nor the arterial opening is perfectly loose ; both have valves. The valves placed at the arterial opening are very similar in their arrangement to those found in the common veins they are however much larger and are usually three in number. Thenconvex and attached edge looks toward the heart while the loose edge, which has two concavities and which is thicker than the rest of the membrane, is turned toward the cavity of the artery. In the centre
Vol. II. 25
194
DESCRIPTIVE ANATOMY.
of the latter we observe a fibro-cartilaginous tubercle ( nod-ulus ). The
blood which comes from the ventricle pushes them toward the circumference of the artery and against its parietes. On the contrary the
blood which tends from its specific gravity to return from the artery
into the ventricle separates them from these same parietes, their loose
edges then touch, and they form a horizontal septum between the
cavity of the artery and the ventricle, which prevents the reflux of
the blood into the latter. The tubercles complete this septum and
close the space in the centre of the artery between the three valves.
The valves of the venous orifice differ from those of the arterial opening, and from all other valves, since they are attached much more firmly, hence they close more completely the opening around which they are placed. A narrow cartilaginous ring, which is not however perfect, exists on all the circumference of the venous opening ; this sometimes ossifies in advanced age, especially in the left portion of the heart, and is situated deeply between the muscular fibres of the ventricle and those of the auricle.
This is the cartilaginous tissue already described as the origin of the external muscular fibres of the heart. The venous valve is attached to this tissue by its posterior edge, but its opposite and uneven edge, unlike that of all the other valves, is not loose ; many flat and solid tendinous filaments, which extend from the base to the summit of the heart, arise from the valve, on which they are often united or pass over it and go to the opposite part of the circumference of the heart, soon unite into larger cords, and are attached to the parietes of the heart, and principally to its fleshy pillars. As the latter shorten when the heart' contracts, the different parts of the valves then approach each other and the opening is forcibly closed. It is necessary that the loose edge of these valves should be thus attached since they must resist not only the weight of the blood like the other valves, but also the action of the muscular parietes of the heart, which forcibly push forward the arterial blood.
5th. The arterial portion of the heart is divided into an upper and lower half, which are separated by the upper part of the valve of the venous orifice at the upper and posterior parts of the ventricles, and which blend together at the summit of the heart, so that the ventricles, although resembling externally an elongated cone, form in fact two arched canals, convex forward, and the greatest convexity of which corresponds to the summit, and are more extensive in this part than in any other.
6th. The reticulated structure of the ventricles is much more distinct than that of the auricles. Some of the fleshy pillars form rounded, elongated projections, terminating in blunt summits (musculi papillares ), which go toward the base of the heart, and from the extremity of which several tendinous filaments proceed to attach themselves to the loose edges of the venous valves. Farther, those fleshy pillars which are attached by their two extremities, as well as those which have
r
ANGEIOLOGY.
195
one end loose, communicate with each other at intervals by tendinous
fibres. The direction of the principal fasciculi is longitudinal, the
smaller which unite the preceding are oblique. Near the summit the
reticulated texture is more and more developed, and the parietes become thinner in the same proportion.
IX. RIGHT AND LEFT PORTIONS.
§ 1303. 1st. The right half of the heart is considerably thinner than the left. This difference is very striking between the two ventricles, where the relation is generally as one to four or to five. Even then we find, as between the auricles and the ventricles generally, that the power of the parietes is in direct ratio with the space passed through by the blood winch comes from them. The greater thickness of the walls of the left ventricle determines the form of the whole arterial portion of the heart. The right wall formed only by the septum is convex, and the left appears fitted to it like a sling.
2d. The substance of the right side, especially that of the ventricle, is softer and looser than that of the left side.
3d. The right side is broader than the left after death.(l) This difference also is most marked between the two ventricles, but it is not yet determined if it exists constantly during life or supervenes only after death.
Many anatomists, particularly Lower, (2) Santorini, (3) Weiss, (4) Lieutaud,(5) and Sabatier, (6) have adopted the latter opinion, while most others favor the first.
This hypothesis has been supported sometimes by the result of measurement, and sometimes by the fact that the left ventricle is as much longer as the right is broader, and sometimes by experiments and observations, from which it has been concluded that the right side appears broader after death, only because it is more distended by the blood which remains stagnant in the lungs from their inaction, while previously the passage of the blood from the left ventricle was not obstructed ; whence the left ventricle seems to be narrower compared to the right, in proportion to the less quantity of pulmonary blood received by it through the pulmonary veins. In men and animals who have died suddenly from the injury of the large vessels, or of those which communicate with the right portion of the heart, when consequently this cause of the distention of the right ven (1) Helvétius, Sur l’inégalité de capacité qui se trouve entre les organes destinés à la circulation du sang , dans le corps de l’homme, et sur les changemens qui arrivent au sang enpassant par le poumon, in the Mêm. de Paris, 1718, p. 222-281.
(2) Loc. cit., p. 34.
(3) Loc. cit., p. 144, 145.
(4) De dextro cordis ventriculo postmortem ampliore, Altdorf, 1745.
(5) Essais anat., p. 230, 231.
(6) Sur /’inégale capacité des cavités du coeur et des vassieaux pulmonaires, in the Mém de Paris.
(7) Lieutaud has brought forward this argument.
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DESCRIPTIVE ANATOMY.
tricle did not exist, the capacity of the two portions has been exactly
or nearly the same.(l) Finally, when the left ventricle is placed in
the same condition by means of a ligature as is the right ventricle at
the time of death; while on the contrary the blood is removed from
the latter by cutting the pulmonary artery, or the vena cava, we find
that the relation between the two ventricles is the inverse of that
which commonly exists, that is, that the right ventricle is narrower
than the left.(2)
The vein's appear much larger than the arteries after death, undoubtedly from the same cause.
To these experiments we may add that we sometimes find the right ventricle narrower than the left from the effect of disease, such as ossification or some other malady of the valves of the aorta, in which case the difference must be explained precisely in the same manner. We have before us several preparations in which, beside a considerable dilatation of the left ventricle arising from this cause, there is at the same time a great contraction of the right ventricle, proving that the results drawn from these facts cannot be opposed, by saying that the dilatation of the right cavity of the heart in the usual state of things should extend also to the left portion from the influence which it exercises on the veins and arteries of the body, and consequently that the right half is really larger during life since the left is itself distended. Since the cause of the greater distention of the right portion, that is, the more difficult passage of blood through the lungs, supervenes only at the moment of death, the opinion that the right ventricle is also more capacious during life cannot be sustained. (3)
That the cause above mentioned is that which increases the capacity of the light portion of the heart at the period of death only, is proved by the fact that the difference between the two portions of the organs varies with the cause of death, and that it increases in a direct ratio with the increase of the obstacle to the circulation of the blood in the lungs. Thus, in those animals killed by drowning, hanging, and suffocation, Colman has found the right ventricle generally twice the size^of the left, although its proportions commonly mentioned are much smaller.(4) In fact, Haller asserts that in one subject he found it three times as large as the left, (5) but the usual estimates are much less than this. Gordon says the relation is sometimes as 5 : 4,(6) Lieberkühn as 3 : 2,(7) Portal as 7 : 5,(8) Helvetius(9) and Legallois,(10)
(1) Weiss, loc. cit. — Sabatier, loc. cit.
(2) Sabatier, loc. cit.
(3) Haller, Elem. phys., vol. ii. p. 134.
(4) On suspended respiration from drowning, hanging , and suffocation, London, 1791.
(5) Loc. cit., p. 133.
(6) System of human anat., vol. i. p. 38.
(7) Hamberger, Physiologie , p. 708.
(8) Mem. de Paris, 1770, p. 245.
(9) Loc. cit.
(10) Did. des sc. méd. vol. v. p. 440.
ANGEIOLOGY.
197
as 6 : 5, Brown Langrish as 11 : 10.(1) Gordon lias found the two
ventricles nearly equal in some cases, (2) and Portal asserts that their
capacity is the same in young people. (3)
These differences in the estimates of authors furnish a new argument against the common opinion, since we should presume that they depend on greater or less accidental obstacles to the pulmonary circulation.
We cannot however deny but that the capacitj^ of the right portion of the heart is a little greater than that of the left, because the blood brought by the vena cava has received the fluid contained in the thoracic canal. It is also proved by the difference relative to the age in the degree of disproportion, this being, directly after birth, less than at a more advanced period of life. (4)
Legallois has also found the right portion of the heart a little broader than the left in every kind of death, both after strangulation and from the loss of blood.(5) The facts related prove only that the right portion of the heart can contract as much as, and even more than the left, in certain circumstances, and that the left is also susceptible of becoming larger than the light, but not that the capacity of the latter exceeds that of the former during life.
4th. The fibres of the right side, especially those of the ventricle, are not arranged in the same manner as those of the left side.
a. The thinness of the right ventricle is attended also with fewer fibrous layers, a fact already pointed out by Senac,(6) but which Wolff has indicated more precisely in saying that the right ventricle is formed of three layers only, while that of the left side presents six, counting the fleshy fasciculi of its internal face. (7) We have not however been able to find this number of laj'ers. Usually we have observed on each side only three distinct layers, two oblique, and one internal longitudinal.
b. The fibres of the right ventricle are flatter and thinner than those of the left. Thus the former form flattened fasciculi, and the second rounded and thicker fasciculi. The latter ramify more ; they are separated by fat, and have spaces between them, while we can hardly distinguish the former from each other except by the direction of their fibres.
e. The fibres of the right ventricle are more oblique and annular, while those of the left are more longitudinal.
d. The layers of the right ventricle, although thinner, are much more distinct than those of the left ventricle ; besides the latter are still
(1) De part.corp hum. fabric., vol. ii. p. 133.
(2) Loc. cit., p. 33.
(3) Doc. cit.
(4) Portal, loc. cit.
(5) TV. du cœur, vol. i. p. 200.
(6) De stratis ßbrarum cordis in Universum, in the Nov. act. Petrop. vol. iii. an 1785, p. 234-238.
(7) Loc. cit., p. 234.
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DESCRIPTIVE ANATOMY.
more similar in regard to direction, which doubtless contributes to make
the left ventricle firmer, bat proves at the same time that we should
exercise some judgment in determining the number and direction of
these layers. Such at least is the positive result of our researches.
This also is the opinion of Wolff himself, who has studied the arrangement of the heart with too much exactness.
5th. The primitive form of the heart, that of a canal curved on itself, is more evident in the left ventricle than in the right.
6th. The nerves of the left side are larger and more numerous than those of the right side.
CHAPTER II.
SPECIAL REMARKS ON THE HEART.
§ 1304. We usually describe first the right half of the heart ; and in order to follow the direction of the circulation of the blood, we begin with the right auricle.
I. RIGHT AURICLE.
§ 1305. The right auricle ( atrium anterius , s. venarum car arum , s. der truin'), forms that portion of the base of the heart situated farthest on the right and forward.
Its form is almost square ; the vena cava superior descends obliquely from right to left, and from behind forward, towards its upper and right angle, and the vena cava inferior ascends in a contrary direction towards its lower and right angle. Notwithstanding this difference in the direction of the two venæ cavæ, we must admit that they unite and form a single trunk in the cavity of the auricle, for they unite on the right forward and backward, and the absence of the left side of their circumference is only apparent, since this side in fact exists, but is dilated to produce the muscular part of the auricle. The upper and left angle of the latter extends into a small blunt appendage, formed like a rounded square, which is observed before the lower paît of the aorta. The lower and left angle is rounded.
We observe transverse fibres on all the circumference of this auricle, directly below the inner membrane of the heart, which, becoming thinner and separating from each other above and below, are prolonged for a small distance around the superior and inferior venæ cavæ. They are thinner where they surround the point of union of the two venæ cavæ forward, and are extended more uniformly, and are smoother on the right side, both on thsir outer and on their inner face.
But the left part of the posterior face of the anterior and unattached wall of the right auricle, which is the most extensive, is uneven internally. This unevenness depends on much larger and transverse fasci
ANGEIOLOGY.
199
culi, which are united by other smaller oblique fasciculi, so as to present a reticulated appearance. These fasciculi, with which the transverse fibres of the auricle are united, appear between two longitudinal
smooth bands which proceed only along its internal face. One of
these tw'o bands, the left, descends a short distance from the anterior
part of the venous orifice of the left ventricle ; the other, the right,
situated almost in the centre of the anterior wall, a little however to
the right, descends toward the left side, along the union of the two
venæ cavæ. These fleshy fasciculi have been called the pectinœal
muscles (AT. pectinati ) .
The posterior wall of the right auricle forms the anterior face of the interventricular septum. We discover in it several remarkable parts, some of which belong to the history of the development of the heart.
On the right side and toward the centre is the fossa ovalis ( fossa ovalis , s. valvula foraminis ovalis, s. vestigium foraminis ovalis), an oblong and rounded depression, which varies much in size. This fossa is very distinct from the posterior wall of the auricle at its upper part, a little less so on its sides, especially on the right, and is generally blended with it below, particularly on the right side. The more extensive it is, the less evident are the limits which separate it from the other parts of the posterior wall. It however not unfrequently presents a similar arrangement even when it is very small.
Most generally it exactly fills the space between the edges of the projection which surrounds it, and it is very tense, but not unfrequently it is much larger, and forms a valve, the loose edge of which corresponds to the left auricle. We almost always observe a greater or less depression above, between its extremity and the upper part of the projection which surrounds it. Very often also we see in this place one or more openings by which the cavity of the two auricles communicate. This arrangement is not constant, and it is entirely independent of the extent either of the valve or of the depression, although it occurs particularly when the valve is very broad. Even when the openings are large and numerous, they seldom descend below the central part of the projection which surrounds the depression, so that the septum of the auricles is complete in regard to the separation of the blood contained in the two cavities.
This place, especially in its upper part, is the thinnest portion of the septum and of the auricle generally. W T e however always observe muscular fibres between the two layers of the internal membrane of the heart, that of the right and that of the left auricle.
The projection which surrounds this depression is formed of reticulated muscular fibres. It is called the ring or the isthmus of Vieussens ( annulus , s. isthmus Vieussenii). Its right portion separates the right and left halves of the septum. Although it does not project at its lower part, it is however complete in this place also.
We observe in its circumference several openings of the cardiac veins, called the foramina of Thebesius ( foramina Thebesii). At the
200
DESCRIPTIVE ANATOMY.
lower end of the inferior edge of the ring a circular fold of the inner
membrane of the right auricle commences, this is called the Eustachian
valve ) or the anterior valve of the foramen ovale ( valvula Eustachii , s.
foraminis ovalis anterior). { 1) This fold extends more or less to the
right, along the anterior part of the orifice of the vena cava ascendens
into the right auricle, so that its lower edge is concave and attached
while the upper is convex and loose within the right auricle. It imperfectly separates below the right and left halves of the right auricle.
This valve varies much in regard to size, form, and texture. It is usually more perfect and proportionally larger in the fetus than at any time after birth. In the adult it is often entirely changed, at least at its upper part, into a reticular tissue, and in many cases some filaments only trace the valve, and these frequently do not exist. It usually contains some muscular fibres, but it is often only a simple fold of the internal membrane.
An intimate relation generally exists between the Eustachian valve and the fossa ovalis, the former being more developed in proportion as the septum formed by the latter between the two auricles is less perfect, and vice versa ; but to this rule there are numerous exceptions.
The valve acts principally in the fetus. At this period of life it conducts the blood of the vena cava superior toward the opening of the septum or the foramen ovale. Hence the relation between it and the valve of this opening.
In the adult it may prevent to a slight degree the reflux of the blood from the vena cava superior, and from the right auricle generally into the vena cava inferior. Directly at the left side of the left branch of the isthmus of Vieussens, between this branch and the venous orifice of the right ventricle, there is a large and rounded opening, the orifiee of the large coronary vein of the heart ( orificium venae coronariœ cordis magnœ).{ 2) This opening is sometimes divided more or less distinctly into several, and generally is more or less perfectly closed by a valvular fold, which arises at its lower part. This fold, called the valve of Thebesius ( valvula Thebesii), has its upper and .concave edge unattached, while its lower and convex edge adheres. Sometimes it does not exist in other cases it is replaced by one or more imperfect transverse bands ; finally, in some subjects there are several, even as many as six, situated one behind another.
(1) Winslow, Description d'une valvule singulière de la veine cave inferieure , à l'occasion de laquelle on propose un sentiment nouveau sur la fameuse question du, trou ovale , in the Mém. de Paris -, 1717, p. 272. Eclaircissement sur un Mèm.de 1-717, Ibid. 1725. — Haller, De valvulâ Euslacliii, Gottingen, 1737. — L. Crell, De valvulâ venœ cavœ Eustachianä, Wittenberg-, 1737.- — Brencle), De valvulâ Eustachianâ inter venam inferiorem dextramque cordis auriculam positâ, Wittenberg, 1738. — Haller, De valvulâ Eustachii prog.r. ii. Gottingen, 1748. — J. M. Diebolt, De foramine ovali, Strasburg, 1771. — J. F. Lobstein, De valvulâ Eustachii , Strasburg, 1771. — C. F. Wolff, De foramine ovali cjusque usu in dirigendo sanguinis motu observationes novœ, in the N. C. Pctrop, vol. xx. p. 357. — H. L. Leveling, De valvulâ Eustachii et foramine ovali, in the Obs. anal, rar f asc. i. 1786.
(2) Wolff, De orificio venœ coronariœ magnee ; in the Act. P elrop. 1777, p. 234-257.
ANCEIOLOGY.
201
II. RIGHT VENTRICLE.
§ 1306. The anterior , pulmonary, or right ventricle ( ventriculus anterior, s. dexter , s. pulmonalis ) is composed of an upper and lower portion, which are separated bj the upper part of the venous valve. The former unites directly to the right auricle, the latter to the pulmonary artery, and its walls are thinner than those of the former. It terminates in a conical extremity, which projects upward and backward above the left ventricle and the septum of the heart. The pulmonary artery arises from this part.
The internal or posterior wall is formed by the septum of the heart and is slightly convex ; the anterior is still more so. The posterior wall is smoother than the anterior at its upper portion and very often entirely so below the arterial opening. The net-woik formed by the projecting muscular fasciculi is much more complete toward its summit than toward its base.
The anterior wall of the pulmonary ventricle is thinnest above toward the septum and thickest below also near the septum. Its thickness when the heart is strong and not very much distended is more than two lines, but less than this in the latter point. The two parts are scarcely a line thick even in those hearts which are neither very much distended nor small.
The quantity of blood in the right ventricle after death varies from one ounce and a half to three ounces.
§ 1307. The venous valve of the right auricle arises from the circumference of its venous orifice. It is called the tricuspid valve ( val vida triglochis , tricuspis ), because, although it forms a single membrane, it is higher in three points than in the short spaces between them, and thus three slips are formed.
Of these, one, which is the largest, arises from the external and anterior part of the circumference of the venous orifice. The other two are smaller and arise from the inner and posterior part of this circumference, one over the other ; so that consequently there is an external and larger slip, and two internal, an upper and a lower slip.
The last two are separated from each other by a space not so deep as those between them and the external. It is then more correct to admit only two slips, an anterior and external and a posterior and internal.
The first is much higher than the second.
The tendinous filaments of the upper extremity of the anterior or external slip are attached to this upper part of the septum. They are few in number. We usually find in the space only one or at most two short muscles, to which are attached those filaments farthest to the left ; the others are inserted in its smooth wall. Most of those filaments which come from the central and lower parts of the edge of
VOL. II.
26
202
DESCRIPTIVE ANATOMY.
this slip are attached to the summits of five or six of the fleshy pillars
coming from the middle and lower parts of the anterior wall.
The filaments which arise from the posterior slips are mostly attached to the smooth folds of the septum, except a few, which are inserted in two or three small fleshy pillars, all of which except the lowest come from the septum.
The arterial orifice generally extends about three fourths of an inch higher than the venous. The sigmoid valves are thin. Their tubercles ( noduli Morgagnii ) are slight swellings, which however are often well marked in the young fetus.
III. LEFT AURICLE.
§ 1308 . The left, posterior, or pulmonary auricle (atrium sinistrum , s. posterius, s. venarum puhnonalium, s. aorticum) is of an oblong square form, considerably more broad than high.
It is separated below and posteriorly from the left ventricle by a circular groove, upward and to the right from the right ventricle by a similar depression. The pulmonary artery, the aorta, and the vena cava superior are also found upward and outward, between it and the right ventricle ; so that the external part of its right and left extremities is alone visible.
Its upper left angle rises into an auricular appendage ( auricula sinis tra ), which goes forward to the left and upward, directly behind the pulmonary artery, separating very much from the rest of the auricle. This appendage, which is narrower, longer, and on the whole larger than that of the right auricle, is circumscribed by rougher edges. It curves three or four times and finally terminates in a sharp summit, below and before the pulmonary artery.
The posterior wall of the lower part, the sinus of the auricle (sinus venarum puhnonalium), receives where it is continuous with the lateral parietes the four pulmonary veins, two on each side, the upper being larger than the lower. One of the two veins of the same side opens directly above the other, while between those of the two opposite sides is the whole breadth of the auricle ; so that the two pairs occupy the whole height of the posterior wall.
The parietes of the whole auricle are muscular and formed principally of transverse fibres. They are smooth with the exception of the appendage. We observe in its whole length an anterior and a posterior series of very prominent transverse fasciculi, united by other smaller and oblique fasciculi, which proceed between two longitudinal bands, situated one on the right the other on the left.
The anterior wall is formed by the septum of the auricles and is also, like the posterior face of the septum, irregular in another respect. In fact we there observe a constant semicircular valve, which is however more or less developed. This valve leaves the upper edge of the transparent point which corresponds to the fossa ovalis of the right auricle (§ 1305 ). It is turned upward and toward the left. Its lower edge
ANGEIOLOGY.
203
is convex and attached, and its upper edge is loose in a greater or less
extent. Sometimes there is only a slight projection in its place.
This valve extends behind the interauricular septum. Its lower edge is attached to the posterior face of the centre of the isthmus of Vieussens, and the space between it and this isthmus forms a small cavity ( sinus septi ), which terminates below in a cul-de-sac. This is only the upper part of the valve of the foramen ovale (§ 1305), which in the normal state always ascends on the posterior face of the isthmus. Of this we are readily convinced when it does not adhere to the isthmus in the centre ; for then the continuity is totally uninterrupted.
IV. LEFT VENTRICLE.
§ 1309. The left ventricle (venir i cuius sinister ) posterior, s. aorticus ) is the strongest of all parts of the heart and forms its figure. Its posterior wall and its anterior wall which forms the posterior face of the septum, are convex externally and concave internally : so that its whole form is oval. The internal face of the posterior wall is very much reticulated ; the anterior wall is smooth at its upper part and reticulated in the lower, but less so than the posterior wall. The fleshy pillars are rounded.
The thickness of the parietes is less toward the summit and greater at the base than in all other parts. In the adult it is five or six lines thick at the base and only three at the summit.
The capacity of the left ventricle varies in the adult from eight to twenty drachms.
§ 1310. Before the round venous orifice we find the mitral valve ( valvula mitralis), composed of an upper and a lower slip. The upper arises directly below or rather before the ring of the sigmoid valve of the aorta, and is attached by slips to three or four fleshy pillars, which all come from the internal face of the posterior wall of the ventricle, some above, others below, and among which we distinguish two particularly, an upper and a lower, which are much larger than the others. The inferior and external slip, which is much narrower, is attached by tendinous filaments to a short but very thick fleshy pillar.
All these fleshy pillars arise from the posterior wall of the left ventricle ; so that those of the upper slip arise near the summit of the heart, and cover those of the lower, so that we cannot perceive the lower slip until we have removed the upper or have detached it from its fleshy pillars.
The orifice of the artery is situated directly over that of the vein. Its sigmoid valves are thick and are generally supplied with tubercles ( noduli Arantii ), which are very distinct.
204
DESCRIPTIVE ANATOMY.
V. SEPTUM.
§ 1311,. In the normal state the septum of the heart completely separates its two halves, even when the valve of the foramen ovale is not united with the isthmus of Yieussens at its upper part. In the venous portion of the heart it is much thinner than the auricles, which it separates, and is much lower, as they project above it. It is not muscular in every part, and generally there are no muscular fibres in the upper part, of the old valve of the foramen ovale.
In the arterial portion, on the contrary, the septum is very muscular and is formed almost entirely by the fibres of the left ventricle. It projects considerably into the right ventricle, while in its posterior face, which forms the anterior wall of the left ventricle, there is a deep depression. Its height equals that of the ventricles. It is triangular and terminates in a point toward the summit of the heart. It is generally from four to five lines thick, and even more than a half an inch thick in those parts where the large fascicidi project above the surface in those subjects which have large hearts. It is thickest below the orifices of the large arterial trunks, and thinnest beyond this point toward the interauricular septum. It is almost always weaker at the summit, where the layers which constitute it are less compact and more easily separated from each other,
CHAPTER III
OF THE PERICARDIUM.
§ 1312. The pericardium (pericardium) (§ 1 293) ( 1 ) is a fibro-serous membrane (§ 354), which entirely envelops the heart and the origin of the large vessels, and unites them with the adjacent parts.
The fibres which strengthen its outer layer and which are very apparent in old men, arise from the central aponeurosis of the diaphragm and extend longitudinally over the serous membrane. They are very much developed, particularly forward and upward.
Its lower face, w’hich corresponds to the lower and flat face of the heart, is intimately united to the upper face of the central aponeurosis of the diaphragm by a very short cellular tissue.
It is covered on the sides and forward by the inner walls of the pleuræ.
Behind, it is attached to the esophagus and to the root of the right lung.
(1) J. M. Hoffmann, Diss. de pericardio, Altdorf, 1690. — A. B. Heimann, De pericardio sano et morboso, Leyden, 1729. — Lanzoni, De pericardio ; in Opp. omn., Lausanne, 1738.
ANGEIOLOGY.
205
§ 1313. The pericardium incloses not merely the heart but also the
origins of the large vessels, whence it is reflected on itself in every
direction to arrive at the centre of the heart.
When examined from before backward and from above downward, we notice the following arrangement :
It envelops the aorta and the trunk of the pulmonary artery forward for about two and a half inches, unites these two vessels very closely, and passes uninterruptedly from one to the other ; so that the corresponding parts of their circumference are retained by a cellular tissue.
The posterior part of these vessels is not covered in the same extent by the pericardium.
From the aorta this membrane passes to the right on the vena cava superior, to about an inch above its entrance into the right auricle, descends obliquely from left to right on its anterior portion, then arrives at the right pulmonary veins, on which it descends to about half an inch from their entrance into the left auricle, then goes on the anterior part of the vena cava inferior, directly below its opening into the right auricle, and wholly surrounds it except a small part of its posterior portion. Thence it goes to the left, on all the surface of the left pulmonary veins, and finally covers the left branch of the pulmonary artery below.
From all these parts the pericardium is reflected on itself. It adheres feebly to the large vessels, but much more strongly to the auricles and ventricles.
As in all other serous membranes, the inner and reflected portion of the pericardium is thinner than the external. It closely envelops thesurface of the parts inclosed by the membranous sac, and, except in those parts where it is reflected, it is entirely separated from the outer layer, although they touch ; so that the circumference of the heart is perfectly loose and is attached only by its upper part.
CHAPTER IV.
OF THE DIFFERENCES OF THE HEART WHICH DEPEND ON THE DEVELOPMENT AND ON THE SEX.
§ 1314, The differences presented by the heart in regard to its development are considerable.(l) They relate to its volume , situation , form , and texture.
1st. Volume. The heart is much larger in proportion to the body in the early periods of life than at a more advanced period. The relation
(1) The principal works on this subject are mentioned in Danz, Grundriss der Zergliederungskunde des ungebornen Kindes in den verschiedenen Zeilen der Schwangerschaft, vol. ii. Giessen, 1793, p. 185-188. — See also Meckel, Mémoire sur le développement du cœur ; in the Journal complémentaire , vol. i. p. 259. — Rolando, Memoire sur la formation du cœur ; same journal, vol. xv. p. 323, vol. xvi. p. 34.
208
DESCRIPTIVE ANATOMY.
between it and the body is as 1 : 120 in the full grown fetus and in
the early years of life, while before this period, in the second and third
month of pregnancy, it is as 1 : 50.
2d. Situation. At first the heart is not oblique, but its summit looks directly forward and a little downward. It is only at the fourth month that it begins to turn slightly toward the left side.
3d. Form. The differences in its form are the most important and relate both to the circumference of the whole organ and to the mode of limiting its cavities. Observers have not decided whether there is or is not in the human fetus a period very near its origin, when the heart forms only a single cavity, composed of several compartments placed near each other. But if this period exists, it passes rapidly, since all the external parts are developed in the fetus at the end of one month.
A. OUTER CIRCUMFERENCE.
a. At first the arterial portion of the heart is much smaller in proportion to the venous. The right auricle especially remains for a long time the largest portion of this organ. The permanent relation however begins to establish itself during the last half of uterine existence.
b. The arterial portion is at first flat and rounded : soon however its breadth exceeds its length. Its summit is at first single and blunt ; but as it enlarges it bifurcates. This phenomenon depends on the fact that the right ventricle from its situation does not at first concur to form the summit of the heart ; but it gradually extends downward and remains separated from the left ventricle by a considerable depression. This groove sometimes continues during life, but almost always disappears after the middle of uterine existence.
c. The right ventricle is at first much smaller than the left : they are soon equal in size : for a certain time the right ventricle is even a little larger, but it becomes smaller during most of uterine existence ; so that it is narrower in the full grown fetus and in the young child. The greater size of the right ventricle seems to result from the obstacles which often disturb the pulmonary circulation at an advanced period of life.(l)
(1) This at least has been observed by Portal ( Sur la capacité des ventricules du
cœur ; in the Mem. de. Paris, 1770, p. 244-246). In the heart of a full grown fetus
the left ventricle contained seven drachms of water, while the right contained only
six and a half. The capacity of the two ventricles was the same in that of a young
child ; in that of an adult the right ventricle contained eighteen drachms of water,
and the left only seventeen. The experiments of Legallois (Diet, des sc. méd., vol. v.
p. 440,) prove that we can introduce
In an adult,
In a child,
grs. of mercury
5 Into the right ventricle, 1172 ( Into the left ventricle 1068
f Into the right ventricle, 828 ! Into the left, not softened I by pressure, - - 658
1 Into the left, softened, 822
ANGEIOLOGY.
207
d. In the early periods of life the upper and pyramidal extremity of
the upper part of the pulmonary ventricle is less distinct from the rest
of the organ than at more advanced periods : it elevates itself also less
above the left ventricle and the septum. This peculiarity is very curious, as precisely the contrary is seen in many mammalia, especially
the ruminantia and the hog.
B. INTERNAL ARRANGEMENT OF THE HEART.
The principal difference presented by the heart in this respect is, that
its septum is imperfect in the early periods of life, whence its right and
left portions then communicate with each other.
a. The interauricular septum is perforated during all fetal existence by an opening called the foramen ovale. This foramen is much greater as the fetus is younger ; so that we may consider the septum as primitively deficient and the two auricles then form a single cavity. The foramen ovale gradually grows smaller and occupies the lower and central part of the septum. The Eustachian valve is found very early directly before it and on the right, so as to occupy all its height. Hence as it arises from the anterior part of the circumference of the vena cava inferior, it separates the right and left auricle in such a manner, that this vein empties directly into the left auricle only. On the contrary, there is no trace of the closing of the foramen ovale on the left side till the commencement of the third month. But about this period this foramen begins to be obliterated by the formation of its valve, which arises from the posterior part of the vena cava.
In a still-born child,
In a seven months’ fetus,
In another about the same age,
grs. of mercury
( Into the right ventricle, 34 ! Into the left ventricle,
I not softened, - - 37
^ Into the left, softened, - 78
Into the right ventricle, 23
Into the left, not softened nor flaccid, - - 34
Into the right ventricle, 21
Into the left, softened, 54
In repeating these experiments, also with mercury, we have obtained the following
results :
In a man 50 years old, In a woman 46 years old,
In a woman 40 years old,
In a man 34 years old, “ 30 “ “ 26 “ - In a boy 16 “ - In a girl 7 months old, In a new born boy which had breathed, In a still-born boy,
R. ventricle
L. ventricle
L. auricle
R auricle
oz. drs.
oz. drs.
oz. drs.
oz. drs.
30
10
25
20
40
22 4
22
15
55
40
41
35
32
15 4
21
25
32 4
28 4
25
22 4
28
20 4
20
18
41 4
21 4
37
29
2 4
1 4
1 4
1 6
1 6
2
1 6
1 2
1 4
2
together 4 ounces.
208
DESCRIPTIVE ANATOMY.
As this enlarges, the Eustachian valve diminishes and recedes from
the septum, while on the contrary that of the foramen ovale approaches
it. The latter also becomes narrower and more tense, especially in the
latter months of pregnancy ; so that it closes the opening more exactly.
The termination of the vena cava inferior in the heart suddenly changes,
and this vessel empties itself no longer into the left auricle but into the
right. This change is also favored by that which takes place in the
situation of the heart, which varies so that its summit corresponds
to the left ; the right auricle is more than usually elevated above the
vena cava inferior, at the same time that the Eustachian valve is removed from the septum and is carried forward.
The valve of the foramen ovale increases from below upward along the lateral edges of this foramen. At the sixth month of pregnancy it has already arrived at its upper part ; it then passes beyond it ; so that â– the interauricular septum is entirely filled, except a small space, which is no longer an opening but a very short canal, formed forward by the upper part of the ring of the foramen ovale and backward by the upper part of the valve.
b. It is not yet well demonstrated whether the ventricles, like the auricles, form at first only a single cavity without a septum, although the development of the heart in the animal series, and the deviations of formation of this organ lead us to this opinion. We have always found a trace of the interauricular septum at the summit of the heart, even in the youngest fetuses we could examine. During the first two months however, or at least till the middle of the second, this septum presents at its upper part a foramen, at first rather large, but it gradually diminishes, and is found below the origin of the large vessels, so that the two ventricles form only one, which is imperfectly divided into two portions. This opening is obliterated at the period when the artery which arises from the ventricles becomes double, instead of single, as it was at first ; that is, when the pulmonary artery, which before was blended with the aorta, becomes a proper and distinct vessel. Its obliteration then much precedes that of the foramen ovale.
4th. Texture. The thickness of the parietes is much greater compared to the size of the cavities during the early periods of life than subsequently, and the greatest size of the heart then depends on this cause.(l)
The parietes on both sides are then equally thick. The difference which always exists afterwards, and which is scarcely perceptible even in a full grown fetus, does not begin to be developed till the second half of uterine existence.
The fibrous texture and the different layers of fibres are always more apparent at the early periods of life than at a more advanced age.
(1) Gordon is mistaken in saying- that the parietes of the heart are proportionally thinner in the early periods of life than at a more remote period ( System of human anatomy , vol. i. p. 53.)
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209
5th. Color. The color of the heart is much blighter when the
subject is younger.
No fat has as yet accumulated on the surface of this organ in the early periods of fetal existence ; but this is generally the case with all parts of the body.
The pericardium is then proportionally thicker than at subsequent periods, and its internal or reflected layer adheres less intimately to the heart.
C. SEXUAL DIFFERENCES,
§ 1315. The only sexual difference seen in the heart is that it is proportionally a little larger in males.
CHAPTER V.
MOTIONS OF THE HEART,
§ 1316. The circumstances in the history of the motions of the heart, or in the heart in its active state, which deserve examination, are,
1st. The changes in its form.
2d. The succession and simultaneousness of the motions in its different parts.
3d. The relation between the cavities of the heart in its different states and the blood.
4th. The number of its motions.
5th. The changes in its situation.
6th. The duration of its motions.
7th. The conditions on which they depend.
§ 1317. 1st. The heart diminishes in contraction and enlarges in dilatation in every directional )
2d. The auricles and ventricles contract and dilate alternately, so that the two auricles and the two ventricles execute the same motions at the same time. (2) The auricles in contracting send the blood into
(1) Sur le changement du figure de cœur dans le style , in the Mêm. de Paris, 1731, hist. p. 33, 40.
(2) The motions of the heart have been carefully analyzed by Laennec with the aid of the stethoscope, by which we can study them more correctly than by opening and inspecting living animals {De l'auscultation médiate, vol. ii. p. 195-227). From this analysis are deduced numerous important practical facts.
In the motions of the heart we must consider their extent, its impulse, the nature, and intensity of the sound and the rythm, according to which the different parts of the organ contract.
1st. Extent. In a healthy and moderately fleshy subject, the pulsations of the heart are heard only in the space between the cartilages of the fifth and sixth true ribs, and under the lower part of the sternum. Those of the left cavities correspond principally to the first point, and those of the right to the second. If the sternum is short, we hear the pulsations in the epigastrium also. When the subject is so fat that
Vol. IT. 27
210
DESCRIPTIVE ANATOMY.
the ventricles, which then contract on it, and throw it into the arteries
at their base. A small quantity of the fluid however always returns
Irom the arteries into the ventricles, from these into the auricles, and
thence into the veins which open into them.
3d. The cavities of the heart are almost entirely empty when they contract. However a little blood always remains, which is attached especially to the reticulated surface of their inner face.
4th. When the ventricles contract the apex of the heart beats against the anterior wall of the chest, notwithstanding that the organ shortens. This arises principally because that the auricles are then filled, both by the blood disgorged by the veins and by that which
they cannot be felt by the hand, the space in which they can be heard by the stethoscope' is sometimes only about a square inch. In thin persons, when the chest is narrow, and even in children, they always have more extent. They may be heard in the lower third, or even in the three lower fourths, of the sternum; sometimes also, under all this bone, at the left anterior and upper part of the chest to near the clavicle, and sometimes, but less manifestly, under the right clavicle. The subject rarely enjoys perfect health when the extent of the pulsations exceeds these limits, so that they are hoard in the left side of the chest, from the axilla to the region corresponding to the stomach ; and to a similar extent on the right side, at the left posterior part of the chest ; finally, on the right posterior part, a successive progress, which would seem to be constant, and which is attended with a progressive diminution in the intensity of the sound. In this respect w r c may state as a principle, that the extent of the heart’s pulsations is directly as the feebleness and the thinness of its parietes, especially those of the auricles, and inversely as their force and thickness.
_ 2d. Impulse of the heart. In contracting, the heart gives a sensation of percussion, raising or repelling the hand, or any other part placed upon the anterior walls of the thorax. In some individuals this impulse is visible, and sometimes causes a very extensive motion, which raises the parietes of the chest, the epigastric region, and even the clothing. It is however but slightly marked when the proportions of the heart are normal, and is often imperceptible in fat people. It is perceptible only during the systole of the ventricles. If the contraction of the auricles sometimes produces a similar phenomenon, it may be distinguished from the first, inasmuch as most generally it consists only in a kind of rumbling, which is heard very deeply in the mediastium. This impulse is generally perceptible only between the cartilages of the fifth and sixth true ribs, or, at most, in the lower half of the sternum, and in some subjects, when the sternum is very short, in the epigastrium. Generally speaking, it is inversely as the extent of the pulsations, and directly, as the thickness of the ventricles.
3d. Nature of the sound. On listening attentively we distinguish during the pulsations of the heart two distinct sounds : one, duller and continued ; the other, quicker, and more distinct. The first is simultaneous with the pulsations of the arteries and marks the contraction of the ventricles; the second is caused by the contractions of the auricles. That heard at the lower part of the sternum belongs to the right cavities; that distinguished between the cartilages of;the fifth and sixth ribs depends on the left cavities. In the normal state, this noise is similar and equal on both sides; and is no where so loud as in the precordial region. It is as much stronger as the parietes of the ventricles are thinner, and as the power of impulse of the heart is less.
4th. Rythm. The duration of the sound caused by the auricles is shorter than of that produced by the ventricles ; hence, the contractions of the auricles do not continue as long as those of the ventricles. There is a well marked but short interval of rest between these two sounds. This observation proves that the heart, like all other muscles, is alternately in a state of action and of rest. We may admit, that of the twenty-four hours, the ventricles have twelve and the auricles eighteen hours of rest ; i n supposing also that the cavities of the heart arc entirely passive in their dilatation. In fact, Laennec admits that in the most general state of the whole duration of time in which the successive contractions of different parts of the heart, occur, a third at most, or even a quarter, is occupied by the systole of the auricles ; a fourth, or a little less, by absolute rest, and a little more than a half by the systole of the ventricles. F. T.
ANGEIOLOGY.
211
flows back from the ventricles, so that the latter are pushed forward :
but it depends also a little on the extension of the arterial trunks at the
moment when the arterial blood which is sent from the ventricles
passes through them.(l) From not attending to these last two circumstances it was for a long time impossible to explain the pulsations
of the heart during* its contractions, except by admitting that it lengthened in performing this motion, which is very improbable.
5th. The mean number of pulsations of the heart in the adult is seventy per minute. But it varies much according to the individual. The pulsations are generally more feeble and fewer in the female. If we except the early periods of life when the contractions of the heart are few, the number of its pulsations is much greater the nearer it is to the period of its formation.
6th. We generally consider the heart as that part in which irritatability continues the longest. But it follows from the observations of Haller, Zimmerman, and Oeder, that there are exceptions to this law ; and the observations of Fontana, Crève, (2) and Nysten,(3) with which our own agree, demonstrate that this is not true, at least to the arterial portion, since the ventricles lose their irritability before the other muscular parts of the body ; but the auricles preserve it the longest, (4) and that the right auricle remains irritable longer than the left. Haller has attempted to prove that this latter difference depends on the circumstance that the right auricle is stimulated longer by the blood within it, (5) but we have often seen it in hearts which were removed from the chest and totally destitute of blood. Nysten Iras observed it also in persons who were beheaded. We then have reason to say it depends on the greater tenacity of life in this part of the heart, and the more as the tenacity increases in animals in a direct ratio with the predominance of the venous system in them,
7th. The conditions of the action of the heart are the same as those of muscular action generally. For this then we refer to the details already mentioned in the first volume.
(1) When the ventricles contract, the point of the heart strikes the left lateral wall
of the chest, between the cartilages of the fifth and sixth ribs. The two causes mentioned by the author, the filling of the auricles and the extension of the trunks of the arteries, doubtless contribute to produce this phenomenon; but we may admit also that while the ventricles contract, their moveable point rises, and performs the motion of a pendulum on the base of the heart, which, being more fixed, serves as a point of support. F. T.
(2) Vom Metallreize , Leipsic, 1796, p. 100.
(3) Recherches dephysiol, et de chimie , Paris, 1811, p. 307.
(4) As Davy observed in experiments for another purpose. See his Researches on nitrous oxide, London, 1800, p. 352.
(5) De cordis m,otu a stimido i\ato, in the Comm. Gott., vol. i,
2 12
DESCRIPTIVE ANATOM V
CHAPTER VI.
OP THE HEART IN THE ABNORMAL STATE.
§ 1318. The anomalies of the heart are divided into two sections, according as they affect the form or the texture of this organ. We shall mention here only the first, having spoken of the latter in the first volume, when treating of the alterations in the texture of the vessels, of the muscles, and of the serous membranes.
§ 1319. The deviations in the formation of the heart embrace anomalies which may exist in number, situation, volume, and figure.
§ 1320. In regard to number, the heart may vary from the normal state in two opposite modes, that is, may be either wholly or partially deficient, or may have supernumerary parts.
The heart is entirely absent only when the upper half of the body is very imperfectly developed, and the head is then usually deficient. However, this rule presents but rarely exceptions of two kinds : for, first, the heart sometimes appears when the head does not exist ;(1) and secondly, this organ is sometimes wholly(2) or partly deficient(3) in monsters where the trunk and head are not very much deformed. We shall speak of the partial absence of the heart hereafter.
The plurality of the heart, the body being simple, is infinitely more rare, however common it may be when the body is double, but is not seen constantly even in the latter case. We know of but one instance of a perfect plurality of the heart where the body was single. We are led to this anomaly by the fissure of the ventricles and by the congenital existence of abnormal and hollow appendages to the heart. (4)
§ 1321. The anomalies in the situation of the heart are congenital or accidental. In the first case the organ exists sometimes within, and sometimes outside of the cavity of the thorax.
When found in the chest it may be,
1st. Straight, and then either perpendicular, or horizontal, or finally placed so that its summit looks upward.(5)
2d. Reversed, having its base to the left and its summit to the right, an anomaly which exists singly or which is attended with the more or less perfect inversion of the other organs. (6)
(1) We have collected all the instances of this anomaly in our Handbuch der pathologischen Anatomie, vol. i. p. 165.
(2) See our Handbuch der path. Anat,, vol. i. p. 414. Besides the cases there mentioned, two have been published since; one by Brodie {Phil. Trans. 1811), and the other by Lawrence {Méd. Chir. Trans.), vol. v.
(3) Rœderer, in the Comment. Gott., vol. iv. — Meckel, Handb. der path. Anat., vol. i. p. 421.
(4) We have collected all the cases of this anomaly in Meckel, De duplic. monstrosa, p. 53, and Handb. der path. Anat., vol. ii. p. 33-45.
(5) Meckel, Handb. der path. Anat; vol. i. p. 418. — Bertin in his work has figured a heart which was situated transversely in the cavity of the thorax.
(6) One case of this kind now before us has been figured in Meckel, De conditionibus cordis abnorm ., Halle, 1802, vol. i.
ANGEIOLOGV.
213
3d . Deeper than usual. ( 1 )
When it exists out of the chest two cases are possible.
1st. The anomaly being slight the heart hangs loosely outward, either in its usual place(2) or higher than it is generally, in the cervical iegion.(3) In this case the pericardium is usually but not always deficient. On the other hand it sometimes but very rarely happens that this membrane is not found even when the heart is situated in the chest, and then it is replaced by the pleura. (4)
2d. The anomaly existing in a greater degree which is also still more rare, the heart is found in the abdomen, (5) a deviation of formation to which the very sloping situation of this organ in the pectoral cavity leads.
The accidental anomalies in the situation of the heart depend on the accumulation of solids or liquids within the chest or the penetration of foreign bodies there, and follow no constant and fixed laws.
§ 1322. Anomalies in the volume of the heart are congenital much less frequently than accidental. They however sometimes have the character of a primitive formation, and are even hereditary in many families. The heart is then too small or too large. We often find both of these anomalies in the different parts of the same heart.
The smallness of the heart(6) is much more rare than its excess in volume. It is often carried to an extreme point although the formation of the organ is unchanged. (7)
As to the excessive size of the heart, we must distinguish the pure and simple increase in its mass, the thickening of its parietes,(8) from the thickening of its parietes with an increase in its capacity, (9) and from its simple dilatation or an increase in its capacity(lO) with or without a thinness of its parietes, since we find all these states sometimes insu (1) Meckel, Handb. der path. Anat., vol. i. p. 417.
(2) Id. Ibid. vol. i. p. 406.
(3) Id. Ibid. vol. i. p. 98, 99.
(4) See our Handb. der path. Anat., vol. i. p. 110.
(5) Deschamps has mentioned an instance of this in Sedillot, Recueil périodique, vol. xxvi. p. 275-279.
(6) We have mentioned several cases in our Handb. der path. Anatomie, vol. i. p. 470-472.
(7) Consult also, on the wasting of the heart, Laennec (De l’ausc. Med. vol. ii. p.
291), and Bertin (Des mal. du cœur, p. 387). The latter admits two kinds ; one where the walls of the heart are collapsed, the other where the same parietes, especially those of the ventricles, are, on the contrary, dilated, and at the same time become thinner ; this is the state termed passive aneurism. F. T.
(8) Different instances of the simple increase of the mass of the heart have been reported by Vetter, Aphorismen aus der pathologischen Anatomie, p. 99. — Legallois, in the Bullet, de l'Ec. de Med., 1813, 1814, p. 69. — Morgagni, Ep. anat. med., 30 to 20. — Burns.
(9) We find several cases of it in Morgagni, Epist. anat. 18 to 28, and 30. — Corvisart, Malad, du cœur. p. 61.
(10) Many instances of this anomaly are mentioned in Burns. — Morgagni, Epist. anat., 18 to 2, and 14. — Dundas, On a peculiar disease of the heart, in the Med. sure . Trans., v©l. i. p. 37.
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DESCRIPTIVE ANATOMY.
luted and sometimes united.(l) The last two are termed aneurisms of
the heart, which in the first case is called active, and passive in the
second. The active aneurism is more common on the left side and
the passive on the right. These two states usually coexist, the left
side being dilated actively, and the right side passively, to a greater
or less degree. (2) Sometimes the parietes of the left side have only
become thicker, and those of the right side are on the contrary
thinner, with or without dilatation at the same time. (3) However
it often happens that one part or the other is diseased, each in its
(1) This distinction neglected by Corvisart who understands by the terms active aneurism and passive aneurism only a dilation of the heart with a thickening or thinness of its parietes, was made by Bertin in 1811, in a memoir presented to the Institute. Bertin admits three distinct forms of hypertrophy of the heart, that is, of its total or partial fleshy thickening : 1st, simple hypertrophy, in which the cavities of the organ preserve their natural capacity, at the same time that the parietes are more or less thickened : 2d. aneurismal hypertrophy , in which the cavities are dilated and the parietes are thickened ; this is the active aneurism of Corvisart : 3d, concentric hypertrophy, in which the thickening of the parietes is attended with a greater or less contraction of the cavities. He also distinguishes two binds of aneurismal hypertrophy ; one in which the parietes are thickened, and the other where the parietes preserve their natural thickness, so that the increase takes place in some measure according to the extent and the circumference, or according to the surface. He has also remarked, that in the hypertrophy of the ventricles the thickness often diminishes from the base to the point, but it is sometimes about the same at the point as at the base, and in some cases is more marked in its centre, and diminishes toward the point and even toward the base. It may be equal to fifteen lines, and more, although Laennec asserts that it never exceeds four or five lines. Sometimes we find in the same ventricles one portion which is dilated and thickened, and another contracted and thickened, or one part thin, while tbe other is thick. We sometimes observe a great difference between the parietes of the ventricles, especially on the right side, and the fleshy pillars, the latter being doubled or tripled in extent, while the parietes are not, or but very slightly, thickened. In other cases, the hypertrophy of the left ventricle seems to take place at the expense of the pillars, which are effaced or are hardly visible. The hypertrophy of the left ventricle is generally attended with that of the septum. We sometimes observe also a hypertrophy of the interventricular septum only. The fleshy pillars of the right ventricle have been found so thickened and intercrossed that there was hardly any cavity. Hypertrophy also often affects both ventricles at once, but not unfrequently they present an opposite state. The point of the thickened ventricle always descends lower than that of the other. The three forms of hypertrophy are observed in the auricles, but the aneurismal is the most common. The thickening is nearly equal in all the extent of the pariete3, especially in the left auricle. The muscular fasciculi of the right auricle sometimes increase in volume. Finally, in certain cases, the parietes of this auricle are so much thickened in all their parts, that they imitate those of the corresponding ventricle. Again, whatever may be the form of the hypertrophy, Bertin admits, as its immediate and proximate cause, an irritation applied to the heart, which increases the activity of the phenomena of nutrition in this organ (Des maladies du cœur, p. 282). He admits also three kinds of dilatation of the heart, or to proper aneurism : 1st, dilatation, with thickening of the parietes, or aneurismal hypertrophy ; 2d, dilatation, with thinness of the parietes ; the passive aneurism of Corvisart, which is more rare than the preceding ; 3d, dilatation of the cavities, they being of their usual thickness, or simple dilatation, which has not hitherto been regarded. To these three classes he adds a fourth, which is doubtful ; the mixed dilatation, in which the parietes of the dilated cavity are thicker in some parts and thinner in others, and of their natural thickness in the rest. (Ibid, p. 368.) Consult also, on hypertrophy of the heart, Lallemand, Observations pour servir à l’histoire des hyper sarcoses du cœur, in the Archiv, gen. de méd. vol. v. p. 520. F. T 23.— Testa. Mal. del cuore, iii. c. xv.
AXGEIOLOGI .
215
usual manner.(l) The disease does not necessarily effect an entire
half. Generally, passive aneurism exists only in the right auricle,
and active aneurism only hr the left ventricle, whether these two
states exist alone, or whether they are both found in the same heart.
Sometimes however, but rarely, the right side is entirely or partially
thicker than usual, or at the same time dilated ; and then sometimes
the left side is also affected and sometimes it is not : sometimes also
it presents a passive aneurism, or at least its walls have become
thinner. Perhaps the passive aneurism is still more rarely confined
to the left ventricle, while all the other parts of the heart are in the
normal state. (2)
These affections are confined to one part of the heart only, much more generally than they are extended to the whole of it. Nevertheless, if we except the active aneurism of the left side, combined with the passive aneurism of the right side, which is frequently observed, we sometimes find hearts which are affected equally in every part. (3)
The diseased cavity of the heart is most generally dilated in its whole extent. A partial dilatation in the form of a cul-de-sac rarely exists.
The substance of the heart is sometimes, but very rarely, thicker in some parts from round excrescences which project on its internal face. We know of but one instance of this arrangement, and the specimen is in our cabinet. This is still more curious, as it throws much light on the formation of the polypi of the heart, which are explained with difficulty unless we admit that one or more of these excrescences are detached from then place of origin.(4)
§ 1323. The anomalies in the form of the heart relate either to its external or to its internal arrangement, or finally to both.
They are congenital much offener than accidental.
§ 1324. The congenital anomalies in the external form are,
(1) We find instances of the active aneurism of the left ventricle in Lancisi, De rep. mort., p. 137. — Lafaye, in the Mém. de Paris, hist., p. 29.— Corvisart, Journ. de méd. vol. xi. p. 257.— We find cases of the passive aneurism of the right ventricle only in Fleury, Bull, de l'Ec. de méd., 1807, p. 124. — Morgagni, Epist. anat., m. 18 to 6.
(2) We find one case in Corvisart, p. 99.
(3) Different cases which prove this proposition, both in respect to the simple thickening of the parietes, and also to passive aneurism, are mentioned in Vetter, loc. cit., p. 99. — Burns. — Morgagni, Ep. anat., m. 18 to 2, 23, 30, ep. 53 to 9. — Corvisart, p. 61, 87. — Testa, loc. cit., vol. iii. ch. xvi. a. 7, 8, p. 361-367.
(4) Laennec relates several cases of this abnormal arrangement ( De l auscultation mediate, vol. ii. p. 344) which he terms globular excrescences of the heart, and which he compares to the excrescences of the valves. Meckel’s mode of explaining them cannot be maintained. Bertin (loc. cit., p. 444) not only admits with Corvisart, Testa, Burns, Creysig, and Laennec, that polypi, or rather fibrinous concretions, may form, during life, in the heart, as in all other portions of the sanguineous system'; but he also adopts Kreysig’s theory, and regards them as resultingfrom an effusion, which occurs after inflammation of the inner membrane of the heart. These concretions are most generally free from all adhesions, at least organic ; but sometimes also they are perfectly organized, and have numerous vessels injected in bright red or black. This important fact, of which Bouillaud has published two remarkable instances ( Obs. et cons. nouv. sur Voblitér des veines, in the Arch. gén. de méd., voi. v.
216
DESCRIPTIVE ANATOMY.
1st. The form of the heart is more rounded ; this is sometimes met
with alone, but is usually attended with several other anomalies already
mentioned, or which remain to be described, as prolapsus, perpendicularposition, &c.
2d. The deep fissure of the summit of the heart, to which our remarks on the preceding anomaly apply.
The accidental anomalies in the external formation are principally the solutions of continuity , which must not be confounded with those which are congenital, for the latter implicate the inner form, and they consist essentially in anomalies of the connection of the two portions of the heart.
Solutions in continuity of the heart are fissures or wounds.
Fissur es(l) occur most generally after those pathological changes which supervene in the substance of the heart itself, or in the arterial trunks. They less commonly depend on external injuries, which do not directly affect the substance of the heart, but act either on the parietes of the thoracic cavity, or on the organs within it.
1st. The changes in the substance of the heart giving rise fissures, are produced principally by inflammation , ulceration , and gangrene, {2) which soften this substance, (3) and gradually destroy it in one or more parts, so that there is finally a solution of continuity during the systole or the diastole. One can imagine that this species of fissures is equally frequent in all parts of the heart.
2d. Those on the contrary which depend on morbid changes supervening in the arterial trunks occur in some points more frequently than in others, and are probably more common in one sex than in the other.
p. 95, and 101), throws great light on the theory of the formation of polypi of the heart, inasmuch as we can no longer doubt that their organization takes place in the same manner as that of the false membranes, and depends en the same cause.
F. T.
(1) Bland, Mémoire sur le déchirement sénile, du cœur, in the Bibliothèque médicale , vol. lxviii. p. 364.— Rostan, Mémoires sur les ruptures du cœur, in the Nouveau, journal de mêdicine, vol. viii. p. 265. — A. J. L. Bayle, Observation de rupture du. cœur, in the Revue médicale, vol. iii. p. 96.— Carrier, Observation sur une double rupture des parois du ventricule gauche du cœur, in the Journ. univ. des sc. médicales, vol. xxxv. p. 358.
(2) Although, strictly speaking, gangrene of the heart is not impossible, it is at
least so rare that those observers in whom the fullest confidence can be placed have not seen it. Thus Corvisart does not hesitate to say that no well authenticated case of it exists. Most of the facts which have been reported, being stated in a faithless manner, should be reeeived only after strict examination and admitted with distrust. Such is the very wise opinion of Bertin ( Des malad, du cœur, p. 408), who thinks that these facts should be considered as acute softenings of the heart rather than real gangrenous affections. F. T.
(3) Laennec first called the attention of pathologists to softening of the heart, of
which he admits two species, one where the substance of the organ is more deeply colored, and the other where it is discolored, or rather has a whitish or yellowish tinge ( De l’auscultation, vol. ii. p. 186). He asserts that he has found this softening in all cases of fevers called essential, when he has attended to them. He does not however consider this as a character of inflammation. Bertin thinks it is caused by inflammation of the heart, which is acute when it is of a deep red or even brownish, and chronic, when the muscular tissue of the organ is discolored and becomes pale or yellowish. F. T.
ANGEIOLOGY,
21Ÿ
Thus the part of the heart most frequently ruptured is the left ventricle, and this accident is more common in the male than in the female, because the ossification of the valves and the contraction of the arterial orifice, which is a consequence of it. are observed in the left more frequently than in the right, and in the male oftener than in the female. When this occurs, the substance of the heart is thinner less frequently than it is thickened and hardened.
The normal difference between the right and left portions of the heart also accounts for the greater frequency of the fissures on the left side, since the right side is less tense and more extensive than the other.
The normal arrangement of the heart explains also why fissures occur in one part of the ventricles rather than in another.
This point is commonly the place where the arterial trunk unites to the ventricle,(l) because there is no continuity in this place between the fibres of the heart and those of the arteries.
The place where fissures occur most frequently, next to this, is the apex of the heart, as there the substance of the organ is thinnest.
Contusions of the chest or the forcible penetration of foreign bodies, as of musket-balls, also tear the heart, even when the parts surrounding this viscus are uninjured.
Besides these fissures, which are visible externally and which pass through the heart entirely, there are others which are much less frequent, and where either the tendons of the venous valves or the fleshy pillars are detached from their points of insertion. The latter almost always result from violent efforts or emotions.(2)
Wounds of the heart are or are not attended with the presence of • the wounding body. In both cases they pass through all the substance of the organ or affect only its surface. Wounds attended with the presence of the foreign body are seen principally after musket-wounds, when the ball, not having power enough to pass through the- heart, remains within it or probably insinuates itself by degrees, the wound cicatrizing behind it as it advances. In both these cases the individual has sometimes survived so severe an injury, but this is rare. (3)
(1) This assertion is not correct. Ruptures of the heart occur always, or most
generally, toward the apex and the anterior part, that is, in the thinnest part. In tins respect, Rostan has observed that the disproportion of the diameter is such, that often, when the diameter of the upper part of the ventricle is sixteen or eighteen lines, which he asserts is the greatest development which it can attain, the apex is only two lines thick. Bayle has mentioned, that of nineteen instances of rupture of the heart, fourteen existed in the left ventricle, principally its anterior face near the apex, three in the right ventricle, one in the apex, and the other in the interventricular septum. In most of the cadavers the heart was remarkably soft, and in some cases a brownish color was observed around the perforation. These two circumstances support Bertin’s opinion, who (Des maladies du cœur) thinks that the preceding erosive inflammation plays an important part in these perforations, as in those of the stomach and intestines. P. T,
(2) Corvisart, loc. cit., p. 256, De la rupture partielle du cœur.
(3) We find an instance of the first case in the Diet, des sc. méd. vol. iv. p. 217, and one of the second in Penada, Saggi sc. di Padova, vol. iii. part 2, p. 59.
Vol II 28
218
DESCRIPTIVE ANATOMY.
Penetrating, cutting, or pricking wounds are always and almost immediately mortal.(l) In order to conceive of a contrary case, we must
admit that the wounding instrument penetrates gradually. (2)
§ 1325. Most of the deviations in form in the inner parts of the heart are congenital. They comprise, 1st, those which cause no derangement except in the circulation of the blood ; 2d, those which derange the formation of the blood.
§ 1326. The deviations of form in the first class consist principally in the abnormal arrangement of the several orifices of the heart.
Among these are :
1st. The abnormal narrowness of the venous orifices of the ventricles .(3) This anomaly occurs most frequently on the left side, and is not rare. The mitral valve is then always thickened, more or less hardened, and often ossified. It is very doubtful if this anomaly ever be congenital. At least it is not so generally.
2d. The abnormal narrowness of the arterial orifices of the ventricles This congenital aberration occurs most frequently on the right side, and almost always results from a contraction, often also from an adhesion of the valves.
(1) Wounds of the heart are generally mortal after a few moments, or at most some hours. Some wounded persons have been known to survive one or five, seven, thirteen, seventeen, and twenty days, after penetrating wounds. See the surgical part of tire article Cœur, by Begin, in the Diction, abrégé des sc. medic., vol. iv. p. 493.
F. T.
(2) Although it did not form apart of our author’s plan to speak of the alterations
in the texture of the heart, we think it necessary to say a word upon its hardening, the theory of which appears to be intimately connected with that of its hypertrophy, its polypi, and its softening, that is with its irritation more or less approaching to the degree usually considered as inflammation. General hardening of the heart has not yet been noticed ; but it may be more or less extensive and sometimes invade an entire half of the heart. It is often confined to the internal or external face, where it is presented under the form of incrustations. The fleshy columns and the septum may also be the exclusive seat of it. It presents several degrees. Simple hypertrophy is the first and ossification the last. There are different shades between these two extremes ; sometimes the substance of the heart, of a bright red color and almost healthy in appearance, resembles in hardness a fibro-cartilage, and resists or grates when cut : sometimes it presents a cartilaginous density and solidity : again it is still harder and sounds like horn, as Corvisart says ; sometimes it resembles earth or sand (Bertin, Des mal. du cœur, p. 401). Ossifications of the heart are not rare in man. Meckel has collected several instances in his Dissertatio de cordis conditionilus abnormibus, Halle, 1802, and in his Manual of Pathological Anatomy. It is curious that in many animals, especially in the ruminantia, there is very often a bone in the heart. This has long been known in regard to the ox and the stag. See on this subject Keuchen, Diss. de ossiculis c cor dibus animalium, Groningen, 1772. — Jaeger, lieber des Vorkommen eines Knochen im Herze des Hirsches; in th e Deutsches Archiv für die Physiologie, vol. v. p. 113. — F. S. Leuckart, Bemerkungen über den Herzknochen des Hirsches ; same journal, vol. vi. p. 136. — We think it worthy of mention, however, that Masuyer has found 1,7 of phosphoric acid, 2 of uric acid, 3 of animal matter, 5,3 of lime, in twelve grains of the ivory substance coming from the ossification of the valves of the heart, from its external face at the base of the right ventricle, and from the aorta, and also from the large branches which arise from it (Journal de la société des sciences, agriculture, et arts , de Strasbourg, 1824, No. 3). The presence of uric acid in this case is remarkable as an analogy with what is seen in arthritic concretions. F. T.
(3) Abernethy, On a diminution in consequence of disease of the area of the aperture, by which the left auricle of the heart communicates with the ventricle of the same f in the Med. chir. trans. vol. i. p. 27.
A.NGEIOLOGY,
219
od. The deficiency or adhesion of the valves, especially those of the
arteries, sometimes occurs, and is not generally congenital but accidental. The absence of the valves is caused by their destruction by
suppuration, and their adhesion results from inflammation and ossification.
4th. Jin excess or deficiency in the number of the valves , which is seen particularly, but yet seldom, in the pulmonary artery, and much less frequently in the aorta. We find four valves more commonly than two.
§ 1 327. The essence of the deviations in form of the second division is an abnormal communication between the systems of red and black blood. They have no influence on the formation of blood, or when they possess it, the arrangement is such that the black blood becomes less venous or the red blood less arterial. In both cases the abnormal union of both the systems of blood may take place in very different parts.
1st. The abnormal communication of the first kind depends,
a. On the insertion of one, of several, or of all the pulmonary veins in the vena cava superior. We have a case of this kind before us.
b. On the existence of an accessory pulmonary artery, which arises from the ascending aorta.(l)
2d. The abnormal communications of the second kind occur either between the auricles, or the ventricles, or in the large vascular trunks. Many or all these anomalies are not unfrequently combined in the same subject.(2)
a. The most simple form is a single heart, consisting of one muscular cavity.
b. Next follows the formation where only one auricle and one ventricle exist, whence a single vessel, the aorta, arises, from which the pulmonary artery branches off, while the pulmonary veins open into the auricle, or even, by a formation still more abnormal, into the vena cava superior.
The formation is more perfect when the heart is divided by a septum into two halves, and the aorta and the pulmonary artery arise by separate trunks, but the septum is imperfect.
c. In this case the septum of the ventricles and of the auricles is perforated and the foramen ovale is open, which is the case most frequently; or,
& Only the septum between the ventricles is perforated, a more un, frequent formation ; or,
e. Only the foramen ovale is open ; this is the most usual.
(1) We have collected all the known cases of this anomaly, in the De monstrodà duplicitate, p. 55, and in Handb. der pathol. Anat., vol. ii. p. 134.
(2) The different degrees and in general most of the species of this class of anomalies are described in our Handbuck der pathol. Anat., vol. i. p. 422-470, vol. ii. p. 133, 134. — Farre, Pathological researches, Essay 1, On malformations of the human hears, London, 1814.— J. C. Hein, De cordis deformationibus quce san g-uinem. renosum cum. arterioso ipisceri permittunt , Gottjngen, 1816.
220
DESCRIPTIVE ANATOMY.
The septum of the ventricles is perforated generally in one deter tm
nate place, viz. the base ; so that sometimes the aorta, sometimes but
more unfrequently the pulmonary artery, arises from both ventricles :
in the latter case the aorta arises as usual, but forms only an ascending
portion, and terminates in the left subclavian artery, and the descending
aorta comes entirely from the pulmonary artery.
The interauricular septum is frequently developed imperfectly, that is, its formation has not followed the course mentioned above (§ 1305), but the pressure of the left auricle can then complete it ; so that the passage of the blood from this auricle into the right becomes impossible. Sometimes however, but more unfrequently, from the absolute or relative smallness or deficiency of the valve of the foramen ovale, this opening is so large, that the right and left auricles communicate freely. This. continuance of the foramen ovale is more unfrequent than the perforation of the septum, although its imperfect closure, produced in the manner stated above (§ 1305), is an anomaly still more frequent than this.
The abnormal arrangements of the large vascular trunks, which render the hematosis imperfect, are,
f. The obliteration or the considerable contraction or deficiency of the pulmonary artery, states which commonly but not always attend one of the anomalies mentioned above.
g. The continuance of the arterial canal, which seldom occurs alone, but is generally attended with one of the anomalies already described Or which remain to be mentioned.
h. The existence of a second pulmonary artery, which arises from the right ventricle and terminates in the aorta. Finally,
The transposition of the origins of the arterial or venous trunks, viz.
i. The origin of the pulmonary artery from the left and of the aorta from the right ventricle, while the venous trunks empty themselves in their proper places.(l)
k. The insertion of the veins of the body into the left portion of the heart, or into the pulmonary veins, or frequently into the pulmonary artery. This occurs in different ways. We have before us a preparation where the large coronary vein of the heart, instead of terminating in the right portion, opens into the left auricle of the heart. In another case, the vena azygos is divided near the heart into two branches, one of which goes to the right, the other to the left auricle. Sometimes the pulmonary arteries evidently anastomose with the azygos vein.
The physiological influence and importance of these anomalies are not the same.
In the first point of view, we may state it as a principle, that the first six arise because the formation of the heart is arrested at an early period of development, and because it is a repetition of the formation of the
(1) Tiedmann has described and figured a case of this anomaly in the Zeitschrift Physiologie,' ch. i. p. Ill, pi. 7, fig. 9.
ANGEIOLOGY.
22 L
heart in some of the lower classes of animals, particularly the crustaceous animals, the mollusca, and the reptiles. The others are normal
in no period of life, but belong to the class of anomalies which affect the
quality of the organs.
Hence also why the former are more frequent. The influence on the hematosis is much more injurious, the greater the mixture of the black and red blood : it is very slight either when the abnormal communication is merely by the small vessels ( k ), or when the communication is interrupted by the arrangement of the parts at the moment when it might be injurious : this occurs in most cases where the foramen ovale becomes open. The derangement is very great in other cases.
The effects which result from them are, frequent recurrence of asthma, extreme weakness of the voluntary muscles, great debility in the nervous system, often a defect in nutrition and development, and a blue color of the body. Death usually supervenes in the early periods of life, although in a few rare cases the patient has lived till the age of fourteen. At certain periods, especially during dentition and at the age of puberty, the symptoms recur more frequently and with greater violence. The cause of these symptoms and the essence of the derangement is, the mixture of venous with arterial blood and the distribution of this mixed blood in the body ; they arise sometimes, as for instance when the pulmonary artery is entirely closed or does not exist, or when the pulmonary artery arises from the left ventricle and the aorta from the right ventricle, because the organs of the body receive pure venous blood.
From the blue color of the skin, which depends upon the venous blood not being changed into arterial blood, (1) this disease has been termed cyanopathia ( morbus r.Å“ruleus , cyanopathia , cyanosis). ( 2)
(1) Bertin has very properly remarked that this explanation cannot be -admitted,
for three reasons : 1st, because cyanosis did not exist in cases where the right and left heart communicated ; 2d, because it did exist in other cases where this communication did exist ; 3d, because that if the blue color of the skin was produced by this deviation of formation, it ought to exist also in other parts, which is not the case. Besides, as Fouquier justly remarks, the skin of the fetus, in which only black blood circulates, is not blueish. Bertin thinks then that the blueish color of certain parts, in different individuals where the two hearts communicated, depends on the stagnation of the blood in the right cavity and in the venous system, which is in a manner gorged with it ; this explanation seems more rational, inasmuch as this anomal v in the formation of the heart is often attended with a contraction of the orifices or of the pulmonary arteries. F. T.
(2) Kwiatkowski, Diss. actiologiammorbi cærulci amplifie ans, Wilna, 1816. — Hein, Diss. de istis cordis deformationibus quœ sanguinem venosum cum arterioso misccri. permittunt , Gottingen, 1816. — J. F. Meckel, Essai sur les vices de conformation du cœur qui s' apposent à la formation du sang rouge ; in th e Journ. complêm. des sc. med., vol. iii. p. 224-301. — Gintrac, Observations et recherches sur la cyanose, ou maladie blue, Paris, 1824. — Louis, Observationes suivies de quelques considerations sur la communication des cavités droites avec les cavités gauches du cœur ; in the Archives generales de médecine, vol. iii. p. 325, 485.
BESCRIPTIVE ANATOÿn.
SECTION II.
ARTERIES OP THE BODY OR OP THE SYSTEM OP THE AORTA
CHAPTER I.
GENERAL EXPLANATION OF THE SITUATION OF THE TRUNK.
§ 1328. The aorta arises most generally and with but few excep • tions by one single stem from the upper part of the left ventricle. At its origin the fibrous membrane is much thinner than in the rest of its extent ; but it is not entirely destitute of this membrane, the thinness of which is supplied by the muscular fibres of the heart, which extend some lines over the valves of the aorta, and the triangular spaces which exist between them. At its base are three sinuses, which correspond to the valves. It goes to the right, first its right side, and then the whole artery passing behind the pulmonary artery, which covers its origin : it comes afterwards on the right side of this artery, and describes a curve before the vertebral column, which is called its urch ( arcus aortœ). The transverse portion of this arch, the part between the right and left sides, is situated opposite the third and fourth dorsal vertebræ.
At the origin of the arch the aorta is entirely inclosed in the pericardium ; but it gradually leaves this membranous sac ; so that most of the arch is entirely loose. We observe on the left the pulmonary artery, which proceeds along the lower part of the arch of the aorta, behind it the right branch of this artery, on the right the vena cava superior, and in front the sternum.
In old age, the lower and ascending part of the arch of the aorta is more or less dilated : it does not form a perfect cylinder ; but it advances farther and projects more to the right than in early life. This change probably depends on a mechanical cause, — the continual impulse of the blood.
The central part of the arch of the aorta is situated before the lower extremity of the trachea, and the curve terminates behind the left branch of the pulmonary artery and the bronchia of the same side, in which place the direction of the artery changes and proceeds from above down â– ward.
The ascending part of the arch is situated on the right of the vertebral column, the transverse portion directly before it and the descending portion on the left : the latter is situated in the posterior mediastinum.
ANGEIOLOGY. 22ÿ
The trunk of the aorta remains on the left of the vertebral column in all its extent.
The ascending portion of the aorta in the cavity of the thorax, called the thoracic aorta ( aorta thoracica ), is directly covered on the left by the inner wall of the left pleura, on the right by the esophagus, and forward first by the left bronchia, then by the posterior part of the pericardium.
At the diaphragm the aorta separates from the esophagus behind, passes through a special openingin this muscle ( hiatus aorticus)(§ 1072), comes into the abdomen, and is called the abdominal aorta ( aorta abdominalis). The latter descends as far as the fourth or fifth lumbar vertebra, where it divides into two branches. It is attended on the right by the vena cava inferior, rests behind on the lumbar vertebrae, and is covered both before and on the left by the peritoneum.
Above and below, it divides in an analogous but not in the same manner, since it gives off, 1st, at its two extremities, the vessels which go to the extremities ; 2d, and besides, at the upper extremity, the carotid arteries ; 3d, at the lower extremity those which supply the pelvic viscera with blood.
The vessels of the thoracic and abdominal viscera, and most of those which are distributed to the parietes of the thorax and abdomen, arise directly from the part between its two extremities.
That part of the aorta between its origin from the heart and that of the left subclavian artery (§ 1335), is called the ascending aorta ( aorta ascendens ), the remaining, the descending aorta ( aorta descendens).
§ 1329. The aorta rarely varies from this general arrangement. Nevertheless it may, in the following modes :(1)
1st. The slightest aberration is when the aorta goes backward too soon, passing immediately on the right bronchia.
Then it sometimes reaches the left side, gliding behind the esophagus and the trachea, as we have observed ;(2) sometimes it remains on the right in a greater or less extent of the vertebral column, for instance, to the base of the chest.
This anomaly may be considered as the first degree of the lateral inversion of the aorta, in which its arch curves more or less from left to right instead of describing its usual curve from right to left.
The arteries which arise from it are also modified in a similar manner ; for we sometimes find four trunks ; sometimes an innominata trunk exists on the left side and two other trunks on the right.
2d. The anomaly is greater when the trunk of the aorta tends to divide. This deviation of formation presents several degrees.
(1) O. Bernard, IHss. de arteriarum e corde prodeuntium aberrationibus , Berlin, 1818.
(2) This anomaly has been seen also by Abernethy (Phil, trans., 1793, p. 59-63)j and twice by Caillot (Bullet, de l’Ec. de Med., 1807, p. 21-28).
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DESCRIPTIVE ANATOMY.
а. Sometimes the aorta is single at its origin ; but, some inches farther, it divides into two trunks, which pass one before, the other behind,
the trachea, and afterwards unite to give rise to the descending aorta,
forming in this manner a ring around the air passage. Hommell has
described a curious case of this kind.
б. A greater degree of this deviation of formation exists as in the case reported by Malacarne.( 1 ) In fact the aorta is single at its origin ; but from this point even, its increased size, its oval form, and its five valves, indicate a division which occurs almost immediately. The two branches on the right and on the left give off, first the subclavian, then the external carotid, and finally the internal carotid, artery , they remain distinct from each other for about four inches, and then they unite to form the descending aorta.
This division of the largest artery of the body is curious in this respect, that it is evidently a repetition of the formation of reptiles, a class of animals in the different orders of which these anomalies constitute the normal state. It leads also to the third kind of anomaly.
3d. In this species of anomaly there is no arch. The aorta divides at its origin into two trunks, one right and ascending, which produces the subclavian and carotid arteries ; the other descends and is the pectoral and abdominal aorta. (2)
§ 1330. The aorta presents anomalies not only at its origin, but also in the rest of its course. Thus, the lower extremity of the arch is sometimes very much contracted(3) or entirely closed(4) in a slight extent ; and although the artery does not divide in this place into two large trunks, the circulation however continues by collateral vessels, which are very much enlarged.
Similar anomalies are observed also, but less frequently, in the lower part of the aorta. Thus sometimes the artery bifurcates higher than usual, to give rise to the primitive iliac arteries, which, before they divide into two large trunks, communicate by a transverse branch. (5)
CHAPTER II.
ARCH OF THE AORTA.
§ 1331. From the arch of the aorta, or from the ascending aorta, arise first, the coronary arteries of the heart ; next, at a certain distance from them, the arteries of the upper extremities and of the head, which come from its upper and transverse part.
(1) Osserv. di chirurgia, vol. ii. p. 119, tab. i. f. 1, 2. — Auctuarium obs. et. icon, ad ostcol. Padua, 1801, tab. iii.
(2) Abhandlungen der Joseph. Akademie , p. 1. tab. vi.
(3) Paris, in Desault, Journ. de. chir., vol. ii. p. 107, 110.
(4) Steidele, Sammlung chirurgischer Beobachtungen , vol. ii. p. 114, 116. — Graham, in the Alcd. chir. trans., vol. v. no. xx. — Cooper, in Farre, loc. cit., p. 14.
15) Pctsche, Sijllog. obs. anat. select ., § 77.
ANGEIOLOGV
22p
ARTICLE FIR SI'.
I. CORONARY ARTERIES OF THE HEART.
§ 1332. The coronary arteries («Æ. coronariœ, cardiacœ) arise directly above the origin of the aorta, and normally above the upper edge of the semilunar valves, so that their orifices, which correspond to the central part of these valves, are not closed when these valves are pressed against the parietesof the aorta. There are usually two, and not unfrequently three ; the third, which is generally smaller than the others, then arises, not above a special valve, but above and very near one of those to which the other two correspond. We once have found four coronary arteries, of which the two supernumerary arte* ries were much smaller than the others, and only branches prematurely detached from them.
A single coronary artery is much more rare. We have seen this anomaly which however is indicated by the less distance between the origins of the two arteries in some subjects, or in the extreme smallness of one of these vessels, the branches of which are entirely replaced by those of the other.(l) The existence of one coronary artery is curious, as it establishes a relation with the normal formation of the elephant.
But however this may be, each ventricle has a coronary artery which almost exactly corresponds to it.
§ 1333. The right , upper , or anterior coronary artery (A. coronaria anterior , s. inferior , s. dextra) is generally but a very little larger and rarely smaller than the left. It arises from the anterior part of the aorta, above the anterior valve, passes under the pulmonary artery, between the upper part of the right ventricle and the right auricle, being covered by the latter, goes forward to the right, and downward in the groove at the base of the heart, turns around the pulmonaiy auricle, and thus arrives at the lower face of the heart, and terminates in the inferior groove of its septum.
In its course it gives off at right angles, both on the right and left sides, several branches, which are often very much curved.
The right branches are smaller and are distributed to the right auricle ; the left, which are larger, go to the right ventricle, and descend longitudinally on its surface to its apex.
The longest of these descends in the inferior groove of the septum., where it anastomoses by several branches with the left coronary artery.
Other ramifications always exist, which are smaller, and are distributed on the anterior part of the left ventricle, and also commun
(1) Barclay (foe. cit., p. 6) has seen the right coronary artery so small thafPit did not extend to the left as far as the septum, and was replap^d o.a this sjde by the transverse branch of the left cöronary artery.
Vor.. IT. 29
(
JD INSCRIPTIVE ANA T O Al Y .
226
uicate with those of the left coronary artery on the flat side of tue heart.
This artery belongs principally to the right half of the heart.
§ 1334 . The left, tipper, ox posterior coronary artery (Jl. coronaria sinistra, s. superior, s. posterior ) is generally smaller than the preceding, and arises between the left auricle and the posterior side of the pulmonary artery, almost always above the left sigmoid valve. It descends on the left, between the auricle and the pulmonary artery, and having attained the groove at the base of the heart divides into two or three larger branches.
Of these one, which is anterior and longitudinal, soon separates into several considerable branches, and descends along the upper groove of the septum to the apex of the heart. In its whole course it gives off branches which anastomose with those of the right coronary artery on the upper face of the right ventricle. Some of the large branches which come from it are distributed on the upper face of the left ventricle.
The second branch, which is transverse, goes backward in the groove at the base of the heart, below the left auricle, and gives several branches, which go to the upper face of the left ventricle. The largest descend along the smooth posterior edge of the heart, some on its upper and others on its lower face.
Finally, the left coronary artery terminates by several small branches, which disappear on the lower face of the left ventricle.
These ramifications, like the preceding, anastomose with the other branches of the left coronary artery and with those of the right which meet them.
ARTICLE SECOND.
OF THE ARRANGEMENT OF THE LARGE TRUNKS WHICH ARISE FROM THE UPPER PART OF THE ARCH OF THE AORTA.
§ 1335 . From the upper transverse part of the arch of the aorta arise the trunks which carry the blood to the head, the neck, the upper and anterior .part of the chest, the upper extremities, and partly to the pericardium, the mammary glands, and the lungs.
There are usually three trunks, which arise a few lines distant from each other, the common trunk, or the innominata artery ( iruncus com munis, s. innominatus) , from whence arise the right subclavian and the right carotid arteries, the left subclavian and the left carotid arteries. The innominata artery is situated farther to the right and in front of the others ; the left carotid artery in the centre and a little farther back ; finally, the left subclavian artery most on the left and farther back than the other two.
ANGEIOLüGT.
227
After birth, the origin of the left subclavian artery sometimes but not
always occupies the highest part of the arch of the aorta, while in the
fetus it arises the lowest. So likewise in the fetus the innominata artery
occupies the highest part of the arch of the aorta.(l) The innominata
artery, in ascending from left to right, is situated in front of the trachea.
It is separated from the vertebral column by the longus colli muscle,
and from the sternum by the sterno-thyroideus and by the left subclavian artery at its side. It is most generally an inch long, rarely longer :
sometimes however it is two inches long, and then the trunk reaches
the inferior edge of the thyroid gland.
The left carotid artery arises more perpendicularly on the left side along the trachea.
The right carotid and right subclavian arteries are shorter than the synonymous arteries on the left side.
The diameter of the vessels of the two sides is the same, or at least those of the right side are but. little larger than those on the left.
The innominata artery usually arises at the side of the left carotid artery ; the left subclavian artery arises from the aorta, at some distance from the latter ; but the interval between them is not always very great.
The abovementioned arrangement is the most common ; we maythen consider it as the normal arrangement. Frequently however, at least once in eight times, (2) the number of the trunks given off from the arch of the aorta varies. This number may'’ be increased or diminished. In the former case, vessels, which are generally branches, arise directly from the arch of the aorta ; in the latter case, one of the three primitive trunks or frequently all of them are blended with each other and form but one.(3)
(1) Sabatier first pointed out this difference. (See his Memoire, sur les ehavgeniens qui arrivent aux organes de la circulation du fœtus lorsqu’il a commence à respirer ; in the Mem de l’Institut ; sc. phys. et math., vol. iii. p. 342.) We are however satisfied, by numerous observations, that it is not by any means constant. Thus
most anatomists have disregarded it. Portal even asserts the contrary ( loc . cit., p.
185), for he states “that the trunk of the left subclavian artery opens into the aorta
a little lower than the other two trunks.â€
(2) Bichat’s assertion that “the arrangement of these arteries is but slightly subject to variation†is incorrect. Haller makes almostthe same statement, and with no more foundation. Nor is Barclay more correct in asserting that “ the cases are rare where a vertebral artery, a thyroid, a thymic, a pericardiac, or an internal mammary arise from the arch.†Only the anomalies of the internal mam mary artery are rare.
(3) Besides all insulated descriptions of the anomalies in the trunks which arise from the arch of the aorta, we may consult the following works, in which this question has been specially examined, and in a more or less general relation : — Bœhmcr, De quatuor et quinque ram is ex arcu aorta: provenientibus, Halle, 1741. — Neubauer, Descriptio anatomica arteriœ innominatœ et thyroideœ imœ, Jéna, 1772.— Huber, De arcus aortce ramis ; in the Act. Helvet., vol. viii. p. 68 102. — Walter, Sur les maladies du cœur ; in the Nouv. Mêm. de Berlin , 1785, p. 57. — Malacarne, Oss. sopra alcune arterie del corpo umano nello stalo prcternaturale e nello stato morboso ; in che Osservaz. di chirurgia, ii. Turin, 1784, p. 119. — Ryan, De quarumd. arteriarum in corp. hum. distrilnitione, Edinburgh. 1810. — Kobenvein, De vasorum d'ecicrsv ahnormi, Wittenberg. 1810,
DESCRIPTIVE aNATOaj.*.
228
§ 1336. The number of the primitive trunks is increased more frequently than diminished. Most frequently we find four trunks, one more than the normal number.
This anomaly does not always occur in the same manner.
§ 1337. Our observations on this subject are principally as follow :
1st. Most generally the left vertebral artery, which is normally a branch of the subclavian artery, arises directly from the aorta. This is the most common anomaly. (1). Notwithstanding the abnormal origin of the left vertebral artery from the arch of the aorta, the number of trunks is not increased ; because at the same time the left carotid artery passes to the right and becomes a branch of the innominata artery. This arrangement is remarkable, for it announces an effort tending to bring the anomaly to the normal type of formation.
2d. After this variety, the most common is that where the inferior thyroid artery, or a portion of it, which is always the thyroid portion, arises from the arch of the aorta. This anomaly occurs on the right side more frequently than on the left, and this vessel then arises, lik e the la-ft vertebral artery, between the innominata and the left carotid artery.
Besides these, we sometimes see coming from the arch of the aorta, in no determinate place, and most generally a little before the large trunks, and not on the same hue with them,
3d. A thymic artery (•/?. thy mica), or
4th. An internal mammary artery (Jl. mammaria interna ).
Less frequently, four trunks arise from the aorta, when the right subclavian artery comes directly from the arch of the aorta. We here find many differences.
5th. The right subclavian artery arises farthest to the right, or
(1) Bichat is also incorrect in saying that ihis anomaly is more rare than an increase in the number of the trunks of the aorta by a most inferior thyroid artery. Sabatier goes even farther, for he does not mention it at all, although he states several Other anomalies which increase the primitive trunks of the arch of the aorta (Anat., vol. iii. p. 7). Portal also is silent in regard to it and only mentions the division of the trunk of the innominata among the causes which increase the number of the arteries given off directly by the arch of the aorta (Anat. med., vol. iii. p. 155). In fact, in another place he states that the left vertebral artery arises directly from the aorta ; but he adds, contrary to what is the fact, that this arrangement is very rare. Monro does not mention it when treating of the anomalies of the trunks which arise from the arch of the aorta ( Outlines , vol. iii. p. 276, 278), although he speaks of them when treating of the varieties of the subclavian artery (loc. cit ., p. 301). Soemmerring, on the contrary, very properly seems to regard it as the most frequent anomaly, and mentions it as the first case where four arteries arise from the arch of the aorta. Boyer ( Tr. d’anat., vol. iii. p. 41) asserts, that the origins of the left vertebral and of a most inferior thyroid artery are equally common and just as frequent. It has been asserted that this anomaly was more rare in the south of Germany than that of the origin of the right subclavian artery directly from the aorta. We are satisfied from observation that this is incorrect ; and we cannot agree to it, because other anatomists of great authority, particularly Haller (le. an.fasc. vi. p. 1), Neubauer {loc. cit., p. 287), Scemmerring and Boyer (loc. cit., p. 25), assert exactly the contrary, and it is refuted by comparing tho number of known cases which njcntipn the different anomgjïes în the trunks of the arch .of the aorta..'
AN'GEIOLOGY
229
6th. This, which is much more common, anses farthest to the left,
below the left subclavian artery.
Between these two formations there are several degrees ; for the right subclavian artery arises
7th. Between the right and left carotid arteries ; sometimes 8th. Between the left carotid and the left subclavian artery.
Of these five anomalies, in all of which the right subclavian artery is insulated from the right carotid, the second is undoubtedly the most frequent. When it exists, the right subclavian artery generally passes between the esophagus and the trachea, seldom before the latter, and goes to the right arm.
9th. This division of the innominata artery is sometimes attended with the transposition of both carotid arteries ; so that
10 th. First the left, then the right carotid artery, next the left subclavian artery, and finally the right subclavian artery arise ; or
11th. Both of the carotid arteries and the right subclavian artery arise in their normal places, but the origin of the left subclavian artery is farther to the right.
But the separation of the right subclavian artery from the right carotid does not necessarily increase the number of the trunks ; for then both carotids are usually blended into one trunk, an arrangement to which may be applied our remarks upon the analogous union occurring when the vertebral artery arises directly from the arch of the aorta.
§ 1338. More rarely five trunks arise directly from the arch of the aorta. When this occurs,
12th. The aorta gives off, besides the usual three trunks, the left vertebral artery, and the right internal mammary artery ; (1) or,
13th. It gives off a right inferior thyroid artery, (2) or, the innominata artery divides into the right subclavian and right carotid-artery, the former arising farthest on the right ; and besides,
14th. The left vertebral artery, (3) or the right inferior thyroid artery, (4) arises directly from the aorta ; or,
15th. The right subclavian artery arises below the left, at the same time that the trunk of the innominata is divided into the subclavian and carotid arteries, and that the left vertebral artery arises directly from it. (5) Finally, sometimes, although seldom, instead of three trunks, 16th. We have six. The aorta then gives origin to the right subclavian and carotid arteries, separately; the right vertebral artery arises between them, and the left vertebral artery springs directly from
(1) Bcehmer, loe. cit. ; in Haller, Coll, diss., vol. ii. p. 453.
(2) We have seen this anomaly twice.
(3) Loder, Nonnull, arter. variet., Jéna, 1781.
14) Patsche, in Haller, Coll, diss., vol. vi. § 44.
(5) Kotjerwein, De decursu vasorurn abnorm., Wittenberg, 1813.
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DESCRIPTIVE ANATOMY.
the arch of the aorta, between the left carotid and subclavian ar
teries. (1)
§ 1339. The number of the trunks is diminished in several modes.
I7th. The left carotid artery is a branch of the innominata, or,
18th. It arises by a common trunk with the subclavian artery of the same side ; or,
19th. The first trunk divides into the two carotid arteries, the second into the two subclavian arteries ; or,
20th. The right trunk is the right subclavian artery, the left is the common trunk of the left subclavian and the two carotid arteries.
The last anomalies are as rare, as the first is common. Our observations have proved that the latter and the distinct origin of the left vertebral artery, are the most common.
§ 1340. Sometimes, when the number of the trunks is neither increased nor diminished, their arrangement varies from the normal state. Abnormal unions and divisions then exist, of which the principal are
21st. The innominata artery is divided, but the two carotids arise by a common trunk, which is implanted in the arch of the aorta, between the two subclavian arteries.
22d. The innominata artery is divided, on the right side into the subclavian and carotid arteries ; but on the left side, both of these arteries arise by a common trunk. The preceding formation leads then to a total inversion of the origin of the vessels.
23d. The innominata artery is divided, but we find a common trunk for both carotid arteries, and 2d, one for the left, and 3d„ one [for the right subclavian artery, which then arises farther from the left side than usual, most generally below the left, and goes to the right upper extremity, passing before or behind the trachea, and most commonly the esophagus.
24th. The innominata artery also gives off, besides its usual branches, the left carotid artery ; but the left vertebral artery then arises directly from the arch of the aorta, between the other two trunks.
§ 1341 . Finally, the least possible anomaly is where only the relative situations of the larger trunks which come from the arch of the aorta are changed : they are,
1st. The trunks arise uncommonly near each other. The left carotid artery then most generally approaches the innominata. This anomaly makes the transition to the union of the two carotids into one. Again, but more rarely, the left carotid artery separates from the innominata, while the left subclavian artery approaches it. This anomaly leads to another case which is rarer, where the left carotid and left subclavian arteries arise by a common trunk.
(1) This anomaly has been seen by F. Muller, formerly demonstrator at Copen baffen, who communicated it to me
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Sometimes also the three trunks are so near each other, that they
in fact arise from the same surface, or form but one stem. This anomaly evidently makes the transition to that where the aorta divides,
directly after its origin, into an ascending and a descending trunk.
2d. The distance between the origin of the trunks is sometimes unusually great. Thus we have found in a child two years old, the left carotid artery nearly an inch distant from the innominata ; the left subclavian artery was also nearly an inch from the left carotid ; the arch of the aorta was extremely sharp, and the left carotid artery arose from the angle formed by the union of the right and left portions.
ARTICLE THIRD
PRIMITIVE CAROTID ARTERY.
§ 1342. The primitive or common carotid artery ( Carotis primitiva s. cephalica ) ascends along the trachea, which generally separates that of the right and left sides. It usually extends to the upper extremity of the larynx, where it bifurcates, at some distance from the angle of the lower jaw, and seldom behind it. It is situated very superficially, especially its central part, so that it is most easily found there. It is covered before by the sterno-cleido-mastoideus, the sterno-hyoideus and the omo-hyoideus muscles ; the internal jugular vein and the pneumogastric nerve are on the outside, and a little in front of it ; the latter is situated between the two vessels ; inside are the trachea, the larynx, the thyroid gland, and also the esophagus ; behind it is the cervical portion of the great sympathetic nerve, the longus colli and rectus capitis major muscles, and the inferior thyroid artery, which separate it from the vertebral column. The inferior thyroid artery seldom passes before it. The primitive carotids are generally situated on the two sides of the trachea, the right a little more forward than the left ; but sometimes, particularly at their lower parts, they are placed somewhat before this canal. The right carotid artery assumes this arrangement, especially when the innominata arises unusually far on the left, and the left when it arises from this trunk. In both cases the arteries cross the interior face of the trachea. These anomalies should be known, as they endanger the carotid arteries in the operation of tracheotomy.
The primitive carotid is inclosed with the internal jugular vein and the pneumogastric nerve, in a very firm cellular sheath.
§ 1343. From the primitive carotid artery arise only small and inconstant vessels, which go to the surrounding parts, but sometimes, and not unfrequently, it gives off, especially on the right side, the superior or the inferior thyroid artery, either wholly or partially ; the latter is more common. The origin of the inferior is, in this case, towards the lower part ; that of the upper, near the upper end of the artery.
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UESCKIPTIVE ANATOMY.
§ 1344. The common carotid artery divides, generally as hign ass
the upper edge of the thyroid cartilage, into two branches, one of
which, the internal carotid, supplies the brain and the eye, while the
other, the external carotid, belongs to the upper part of the neck, the
skull and the face. It sometimes bifurcates much higher up, opposite
the upper extremity of the styloid process, but not till it has given off
the larger of the longer branches of the external carotid.(l) This
arrangement is very analagous to that where the primitive trunk does
not divide into two large branches, but having given off the branches
of the external carotid artery. (2) This anomaly consists evidently in
the premature division of the trunk, while its branches are given off too
soon. In some few cases the division extends much farther, and
attains even the trunk of the primitive carotid. This trunk then begins
to divide very soon, and it sometimes bifurcates, opposite the sixth
cervical vertebra, but the two branches remain connected with each
other.(3)
The distance between the place of bifurcation and the thyroid cartilage is the same at all periods of life : (4) but the distance between the bifurcation and the angle of the lower jaw is much greater in the child than in the adult, on account of the development of the teeth, so that during early life the two large inferior branches are loose for some distance.
These two branches ascend almost perpendicularly. Below they are situated directly at the side of each other. The internal is at first more superficial than the external carotid, but it afterwards becomes deeper. Their proportional volume is not always the same. The differences depend partly on the age, partly on the distribution of the external carotid artery.
In the first respect, the internal carotid artery is always larger than the external in infancy, on account of the size of the brain : in the second, the external is larger than the internal carotid in the adult, when it gives off the superior thyroid artery, and smaller than it, on the contrary, when the latter comes from the prmitive carotid.
I. EXTERNAL CAROTID ARTERY.
§ 1345. The external carotid artery ( Carotis externa, s. facialis, s. A. p encephalic a) ascends under the posterior belly of the digastricus muscle of the lower jaw, is situated between the ear and the ascending branch of the lower jaw, where it is entirely covered by the parotid gland, and divides at the neck of the lower jaw into a superficial branch, which is the temporal artery, (Jl. temporalis ) and a deeper seated
(1) Burns, Surgical anatomy, Edinburgh, 1811, p. 95, 96.
(2) Idem, ibid., p. 95.
(3) Idem, ibid., same page. — We regret that the author does not say whether the anomaly existed on the two sides or only on one side, (perhaps the left';)
(4) Idem, ibid., p. 379.
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branch, the internal maxillary artery. ( A . maxillaris interna.) But it
always gives off large branches, before it bifurcates. These branches
generally detach themselves gradually, one after another. Sometimes,
however, the external carotid artery forms a short trunk, which divides
directly above the bifurcation of the primitive carotid into the large inferior branches, and the broad continuation of the trunk.
§ 1346. Before bifurcating, the external carotid artery gives off branches principally in three directions : forward, backward, and inward.
A. ANTERIOR BRANCHES.
§ 1347. The anterior branches are the superior thyroid artery, thtr lingual artery, and the facial artery.
1. SUPERIOR THYROID ARTERY.
§ 1348. The superior thyroid artery (A. thyroidea superior) is the lowest branch of the external carotid artery. Its origin varies : it geneerally arises some lines above the bifurcation of the primitive carotid ; but it not unfrequently detaches itself at the bifurcation, or below, and even from the trunk of the primitive carotid ; sometimes an inch below its bifurcation.
Its size also varies, and it is in the inverse ratio of that of the inferior thyroid artery. When the latter is entirely deficient, the superior is much larger than usual ; it is on the contrary very small, when the inferior thyroid artery is very large, or when the lowest thyroid artery exists.
Sometimes, but unfrequently, it arises by a common trunk, with the lingual artery, and in some subjects this trunk comes from the primitive carotid.
On the other hand, we not unfrequently find the superior thyroid artery double, because the branches which it generally gives off are detached lower than usual. The arrangement and size of the left and right thyroid arteries vary ; sometimes one of them is deficient, while the other is very large.
§ 1349. When the artery does not arise much lower than usual, nor from the primitive carotid, it always descends inward and forward, being at first slightly concave above, and very tortuous. It sometimes gives off a large branch immediately after arising, which detaches itself from its posterior and inferior part, and goes to the sterno-cleidomastoideus muscle. It then soon divides into an upper and a lower branch. Sometimes it bifurcates near or even at its origin.
The upper or laryngeal branch (ramus laryngœus ) arises from the external carotid artery, according to our observations, once in eight tim<^. It goes downward, forward and inward, on the thyroid cartilage, and frequently gives branches to the omo-hyoideus,the sterno-hyoideus, the stevno-thyroideus, the hyo-thjuoideus and the cvico-thvroidcits
Yon. II ‘ 30
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DESCRIPTIVE ANATOMY.
muscles, which come sometimes from the lower branch, or directly from
the external carotid artery : furnishes a large anastomotic vessel which
goes across the cricoid cartilage, and unites with the branch given off by
the synonymous artery opposite ; finally it penetrates within the larynx,
passing generally between the hyoid bone and the thyroid cartilage,
sometimes, but more rarely, near the upper edge of the latter, by an
opening which exists there, or even between the cricoid and the thyroid
cartilages.(l) Having arrived at this organ, it distributes itself upon
its internal membrane, and also to its muscles, anastomoses very frequently with the synonymous artery of the opposite side, and even sends
ramuscules outside of the larynx, which communicate on its surface
with those of the other side, and with the ramifications of the thyroid
branch.
The inferior or thyroid branch ( R. thyroideus ) is the continuation of the trunk ; it sometimes furnishes many or even all the muscular branches which we have described as coming from the laryngeal branch ; but small twigs always arise from it and go to the middle and inferior constrictors of the pharynx and to the crico-thyroideus muscle. After which it descends downward into the thyroid gland, and generally divides, at its upper extremity, into two branches, a posterior and inferior, and an anterior and superior, which soon subdivide. The former penetrates posteriorly into the thyroid gland, and anastomoses along its posterior face with the branches of the inferior thyroid artery ; the other proceeds along its upper edge, gives off considerable branches which expand on its anterior face, and anastomose, by very large vessels, with the synonymous branch of the opposite side.
When the superior thyroid artery is divided into two separate trunks it often happens, but not always, as one might think from what several anatomists say, (2) that the laryngeal branch is distinct from the thyroid branch, and situated above it. Sometimes however, but very rarely, the superior thyroid artery gives off only the trunk of the muscular branches and the laryngeal branch.
II. LINGUAL ARTERY.
§ 1350. The second branch is the lingual artery (v3. lingualis, s. sublingualis, s. ranina), which arises farther inward, most generally a few lines, and sometimes an inch, above the preceding, and rarely by a
(1) We have remarked that this is the most common arrangement ; so that our observations in this respect agree with those of Mayer (toe. cit., p, 249), and with Bichat ( loc . cit., p. 149), who both say that the laryngeal branch commonly penetrates into the larynx by passing between the hyoid bone and the thyroid cartilage. Murray (loc. cit.. p. 11) indicates exactly these three arrangements, but does not say that the first is the most frequent. Scemmerring (p. 131) entirely neglects this, and speaks only of the two which are less frequent. Sabatier (p. 115) mentions only the third.
(2) Mayer, (loc. cit., p. 49) asserts, but wrongly, that the laryngeal always arises a quarter of an inch above the thyroid artery. Sabatier (loc. cit., p. 15) ; Soemmering (loc. cit., p. 131); (Portal, foe, cit., p. 159).
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trunk in common with the superior thyroid artery, but more frequently,
and nearly once in seven times, with the facial artery. It is generally
a little larger than that we have mentioned.
This artery curves considerably, and its convex part looks upward, passes then directly over the large horn of the hyoid bone, goes horizontally forward, glides between the middle constrictor of the pharynx and the hyoglossus muscle, and then ascends towards the base of the tongue, where it recommences, and then goes horizontally forward, along the inferior face of this organ.
From its posterior part arise, 1st, several branches, which go to the hyo-glossus muscle and middle constrictor of the pharynx, and which, having passed through the latter, enter the digastiicus and the thyrohyoideus muscles, and the submaxillarv gland ; 2d, a branch which goes downward and inward, between the genio-glossus and the geniohyoideus muscles directly on the hyoid bone, gives branches to these muscles, especially to the first, and anastomoses with that of the opposite side. It is called the hyoid branch (I?, hyoideus).
From the central ascending part aiise one or more dorsal arteries of the tongue ( ll dorsales linguae ), which go downward to the posterior part of the tongue, on the inside of the hyo-glossus muscle, ascend upon the back of this organ, and advance to the epiglottis.
The lingual artery divides, in front of the hyo-glossus muscle, into a ranine and a sublingual artery.
The ranine artery (A. ranina) is larger than the other, and is a continuation of the trunk. It extends deeply between the lingualis and genio-glossus muscles, proceeds forward, gives off several branches in its course, and finally anastomoses with that of the opposite side, behind the summit of the tongue, at the upper end of its frenum.
The sublingual artery (A. sublingualis ) is more external and more superficial than the preceding. It passes over the mjdo-glossus muscle, between it and the sublingual gland, gives off branches to it, to the hyo-glossus muscle, to the lingualis muscle, and to the proper membrane of the mouth, passes over the mylo-hyoideus muscle, and anastomoses with the inferior maxillary branch of the facial artery.
This artery sometimes arises from the facial.
III. FACIAL ARTERV.
§1351. The third branch, the facial or external maxillary artery [A. facialis , facialis anterior, angularis, maxillaris externa), varies in respect to its origin, size, and extent ; it is commonly the largest of the three anterior branches of the external carotid, and supplies all the anterior part of the face ; but sometimes also it extends only to the angle of the mouth, and the other branches are supplied from the temporal artery. There is scarcely a vessel which varies so much asihis. even in the two sides of the same body.
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DESCRIPTIVE ANATOMY.
It passes under the posterior belly of the digastricus muscle to go to
the angle of the lower jaw. In this place it proceeds first horizontally
behind and within the inferior edge of the lower jaw, then goes obliquely upward and forward on the inside of this bone and of the upper
jaw.
It frequently gives of!’, directly above its origin, the inferior or ascending palatine artery (Ji. palatina ascendens , s. inferior ), which usually arises from the ascending or inferior pharyngeal artery (A. pkanjngœa ascendens) ; we shall describe it with that.
It then gives small ramuscules to the digastricus and stylo-hyoideus muscles.
Farther on, it gives off considerable branches which go to the submaxillary gland ( R . glandular es), and goes forward in one of its grooves. Farther onward, it gives off one or more ramuscules to the pterygoideus internus muscle.
It then furnishes the submental artery ( R . submenlalis). This arises near the lower edge of the lower jaw, and proceeds along it, directly below the attachment of the mylo hyoideus muscle, and over the anterior belly of the digastricus muscle, gives ramuscules to both of these muscles, anastomoses with the sublingual artery, and thus goes forward, where it communicates with that of the opposite side, on the centre of the lower edge of the lower jaw. Thence it reascends into the substance of the lower lip, to which it gives twigs, as also to the skin of the chin, and anastomoses with the descending branches of the coronary artery of the lower lip, and also with those of the inferior dentar artery, which emerges from the mental foramen.
When the sublingual artery is a branch of the facial it arises a little, and even in most cases directly before the submental.
The continuation of the trunk, or the proper facial artery, turns upon the lower edge of the lower jaw, generally directly before the anterior edge of its ascending branch, thus attains the outer face of this bone, descends very obliquely between the masseter and the triangularis oris muscles, arrives at the angle of the lips, and gives off in this place several branches, which enter the masseter, the triangularis and the buccinator muscles and the skin.
About the centre of the space between the angle of the mouth and the under edge of the lower jaw, it generally divides into two branches. One, the continuation of the trunk, goes directly upward ; the other is smaller, and proceeds more obliquely inward and forward.
The latter is the inferior coronary artery of the Up {A. coronaria labii inferioris). It passes under the triangularis oris muscle and proceeds toward the lower lip, gives several branches to this muscle, to the levator menti, and also to the membrane of the mouth, and anastomoses both with its fellow of the opposite side and with the twigs of the submental and inferior dentar artery.
This artery is sometimes much smaller on one side than on the other. In some subjects it is even entirely deficient, and is then replaced bv
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that of the opposite side. Sometimes it arises much higher and comes
from the superior coronary artery of the lip. In some cases it is double :
one of the two then arises much above the other ; but the two arteries
taken together are not larger than that of the opposite side : sometimes
the two branches into which the lower coronary artery of the lips is
divided are very small.
After giving off this branch, the facial artery winds tortuously upward and inward. Arrived as high as the angle of the mouth, it generally divides, a little above this point, into two branches.
The larger goes inward and forward, between the fibres of the orbicularis oris, and is called the superior coronary artery {A. coronaria labii superioris). This artery proceeds directly over the loose edge of the upper lip, gives ramuscules to the orbicularis oris, to the levator labii superioris, to the skin, to the buccal membrane, meets that of the opposite side and anastomoses with it by a broad communication similar to that between the inferior coronary arteries. The two coronary arteries usually anastomose together in two places by large branches : sometimes the anastomosis between the arteries is very small on one side, but is replaced by a very large branch, which arises higher up from the facial and which communicates with the artery of the septum of the nose.
Both coronary arteries are very tortuous, but the upper is more so than the lower. Both anastomose with the synonymous arteries of the opposite side, and these anastomoses are proportionally the largest in the body, when we consider the vessels between which they occur.
The superior coronary artery always gives off from its centre, where it anastomoses with that of the opposite side, a branch, which goes upward toward the nasal septum, which is called the artery of the septum of the nose {A. nasalis septi). Sometimes this artery is single, sometimes double, and even triple, at its origin : in the last two cases-it is frequently given off by the coronary artery of one side ; but however this may be, it divides near the septum of the nasal fossae into at least two branches, a right and a left, each of which proceeds along the lower edge of the septum and the inner part of the corresponding nostril to the end of the nose, and also sends ramuscules, which reascend on the cartilaginous septum.
Besides these branches, the coronary artery gives off sometimes before, more externally and on one side only, or on both, another considerable branch (R. pinnalis), which goes to the ala and the outer part of the nostril ; but this branch more frequently comes from the next one.
The facial artery, after giving off the superior coronary, consists only of a smaller branch, which may be called the common external nasal artery (A. nasalis externa communis). This artery is very tortuous, and ascends obliquely forward under the levator labii superioris muscles, to which it gives ramuscules, goes toward the nose, and anastomoses by considerable branches with the infra-orbitar artery. It
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DESCRIPTIVE ANATOMY.
usually gives off, opposite the nostril, the lateral arteries of the nose
( R . pinnules , s. laterales nasi), and also sends off numerous smaller
arterial twigs, which anastomose with each other and also with those
of the septum and their corresponding ones of the opposite side, which
are called the dorsal arteries (R. nasales dorsales ), and which always
communicate on the nose by several large or small branches with the
ophthalmic artery. Finally, it terminates on the back and side of the
nose, and never, even in its greatest degree of extension, goes beyond
the upper edge of the cartilaginous portion of this organ.
The two coronary and the common external nasal artery, and more frequently only the superior coronary and the latter, sometimes arise not only from the above facial but also from the transverse facial artery, which then is much larger, while the other is smaller, although the facial artery is not necessarily more developed at its lower part ; we likewise observe in other subjects that this artery is very much developed at its upper part, although the lower part does not produce more branches than usual. We have seen the sublingual artery coming from it at least several times, and the facial artery at the same time was as large as usual. In other cases, on the contrary, it gives off neither of the two coronary arteries, while the sublingual artery arose as usual ; but the submental artery was uncommonly small.
Hence it appears that the facial artery is always the principal source of communication, 1st, between the superficial and the deep-seated branches of the external carotid by its anastomoses with the infra-orbitar, the nasal, and the dentar arteries ; 2d, between the external and the internal carotid arteries by its anastomosing with the ophthalmic artery.
§ 1352. Numerous small branches, which go to the masseter and pterygoidei muscles and to the parotid gland (/i. masseterici,pterygoidei , et parotidei ), arise externally and internally from that part of the carotid artery situated between the ascending branch of the lower jaw and the ear.
A larger anterior branch, the transverse facial artery, which will be described hereafter, rarely arises from its upper extremity, directly below its division.
B. INNER BRANCH.
I. ASCENDING OR INFERIOR PHARYNGEAL ARTERY.
§ 1353. Most generally only one branch arises from the inner face of the external carotid artery ; this is the ascending or inferior pharyngeal artery {.Il . pharyngcea ascendens , s. inferior , s. posterior ), which comes sometimes from the bifurcation of the primitive carotid, somerimes from the origin of the internal carotid, but more frequently from
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the occipital artery, (1) and is sometimes replaced by the branches of
the facial artery.
If it is a branch of the external carotid, it arises very deeply, most generally above the inferior thyroid artery ; so that it is the second branch from the trunk . but sometimes it comes higher up and even above the facial artery.(2)
It is sometimes double : then the two inferior pharyngeal arteries rarely come from the external carotid ; one arises from the latter, and the other from one of the secondary branches above described, or from the internal carotid artery. (3)
It is always the smallest branch of the external carotid artery.
It goes perpendicularly upward, on the inside of the external carotid artery, and in the same direction with it, between it and the pharynx.
It gives off first the descending branches to the constrictors of the pharynx, and to the anterior and lateral muscles of the neck.
A little farther it divides into two branches, one of which, the pharyngeal branch, (R. pharyngœus ) is distributed principally to the constrictors of the pharynx, and communicates with the pharyngeal branches of the superior thyroid artery ; the other is termed the posterior meningeal artery, («d. meningœa posterior ) ascends through the posterior foramen lacerum of the skull, or through a special opening near the occipital condyle, and is distributed to that part of the dura mater which lines the lower part of the skull.
C. POSTERIOR BRANCHES.
§ 1354. The posterior branches of the external carotid artery are, 1st the occipital , and 2d the posterior auricular artery.
1. OCCIPITAL ARTERY.
§ 1355. The occipital artery («3. occipitalis) is a considerable branch, but much smaller than the three anterior branches, which usually arise opposite the lingual or the facial artery ; seldom or never above or below them. It rarely comes from the internal carotid artery. It is very deeply situated ; goes upward and backward, often gives off, soon after arising, branches which go to the posterior belly of the digastricus muscle of the lower jaw, then a descending branch, which
(1) Scemmerring states that it sometimes arises from the superior thyroid arterjL AVe have never seen this, nor is it mentioned by any other anatomist, Scemmerring', it is true, quotes Mayer ; but the laryngo-pharyngean artery ( A . laryngo-pharyvgcea) described by Mayer, is the laryngeal branch of the superior thyroid artery, and describes the inferior pharyngeal artery as the posterior artery of the throat,
(2) Bichat asserts that it arises between the facial and lingual arteries. Our observations lead us to think that SÅ“mmerring is more correct in saying that it rarely arises higher than the lingual. Murray places it behind the facial, but adds that its origin is near that of the lingual. Portal also places it nearly opposite this latter, as do Sabatier and Mayer. Boyer states that it arises opposite the facial.
(3) Scemmering asserts that when it is double, the lower trunk arises from the prim tive carotid, and the superior from the internal carotid. This arrangement exists sometimes, but it is not the law. That mentioned by us is much more common.
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DESCRIPTIVE ANATOMV.
goes to the sterno-cleido-mastoideus muscle and the upper lymphatic
glands of the neck, higher up, gives off wholly or partially the ascending pharyngeal artery, then extends below and deeply between the
transverse process of the first cervical vertebra and the mastoid process
of the temporal bone, continues its course backward, passing under the
complexus minor muscle, then assumes a horizontal direction, gives
branches to the upper extremity of the sterno-cleido mastoideus, to the
complexus minor, to the transversalis colli, to the small lateral and
posterior muscles of the head, and then ascends on the occipital bone,
covered by the upper part of the splenius muscle, to which it gives
branches. It is then called the superficial occipital artery, proceeds
directly below the skin, on this bone to the vertex, terminates in a large
anastomosis, formed by its branches with each other and with those
of the frontal, the superficial temporal and the synonymous artery of
the opposite side.
At the place where the occipital artery leaves the space between the transverse process of the first cervical vertebra and the mastoid process of the temporal bone, to pass on the obliquus capitis major muscle of the head, it always gives a deep or descending branch. This branch being sometimes very considerable, and nearly as large as the continuation of the trunk, we may then admit that the artery divides at this place into a superficial and deep-seated branch. When this is the case, it descends to the middle of the back, between the splenius, complexus, digastricus and transversalis colli muscles. Sometimes, however, it is very small, and then it is distributed in the small posterior muscles of the head.
The deep-seated branch anastomoses many times with the vertebral artery, and with the cervical branches of the inferior thyroid artery.
From the superficial occipital artery constantly arise one or several branches, which pass into the cranium through the mastoid foramina ; more rarely through the large occipital foramen or the foramen lacerum, which are distributed to the posterior and inferior part of the dura mater. They are termed the posterior meningceal arteries. (A. meningeœ posteriores ab occipitali.)
2. POSTERIOR AURICULAR ARTERY.
§1350. The posterior auricular artery (A. auricular is posterior) is generally much smaller than the preceding, and arises a little above it, in the substance of the parotid gland, and is generally separated from it only by the stylo-hyoidcus muscle. Sometimes it arises from this artery, and rarely somewhat higher, directly below the division of the external carotid artery into the superficial temporal and the internal maxillary artery. It goes upward, at the side and behind the trunk of the external carotid artery, and passes through the parotid gland, near the mastoid process. There it gives, 1st at its lower posterior
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part, branches which go to this gland, to the posterior belly of the digastricus muscle, to the stylo-hyoideus and to the upper part of the sternocleido-mastoideus muscles ; 2d, from its superior and anterior part, an
ascending branch, the stylo-mastoid artery (A. stylo-mast oidea), which
furnishes minuscules to the auditory passage, penetrates into the canal of
the facial nerve through the stylo-mastoid foramen, distributes itself to
the mastoid process, to'the tympanum, and also to a portion of the labyrinth, and anastomoses with a branch of the middle meningeal artery.
The trunk of the artery then divides at the level of the mastoid process into two branches, an inferior or muscular and a superior or auricular branch.
The inferior branch goes transversely outward, over the upper part of the splenii muscles, gives minuscules to these muscles, to the trapezius and to the skin, anastomoses with the superficial occipital artery, and advances toward the occiput.
The superior branch goes upward and backward. It usually divides into two or three branches, one of which, the more transverse, goes backward to the mastoid process, and gives branches to it, also to the occipitalis muscle ; while the other, or the others, attain the posterior part of the concha, distribute the small arteries to the retrahentes auriculæ, and to the transversus auriculae muscles, then pass over the concha, and thus come on its internal face, where they lose themselves in the skin and the mucous membrane.
D. TERMINATION OF THE EXTERNAL CAROTID ARTERY.
§ 1357. The external carotid artery terminates at the neck of the lower jaw in two trunks, a superficial, the temporal artery ; the other deep-seated, the internal maxillary artery.
I. TEMPORAL ARTERY.
§ 1358. The temporal artery (A. temporalis) is smaller and more superficial than the internal maxillary, and continues in the direction of the trunk. It goes upward and outward. Its branches may be divided into anterior and posterior.
The anterior branches are principally the following :
1st. The first branch is often the upper masseteric artery (A. masse, terica superior ) which penetrates sometimes to the external and sometimes to the internal layer of the masseter muscle, but frequently comes from the next.
2d. The transverse facial artery (A. transversa , s. transversalis faciei){ 1) is the second, often the first branch of the artery, and arises
(1) Scemmering ( loc . cit.. p. 196) mentions it as arising from the external carotid artery, before it bifurcates, and says also that it sometimes comes from the internal carotid artery, and cites as authorities Mayer, Murray, and Walter. But Murray states expressly that it is the fourth branch of the external temporal artery (p. 17).
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directly above the bifurcation of the external carotid artery. Sometimes, but unfrequently, it arises from the external carotid artery, and
most generally from the bifurcation. It goes forward, with the canal
of Stenon, on the masseter muscle, directly below its upper edge, gives
off the superior masseteric artery, when this does not come from the
temporal artery, sends several minuscules to the skin, penetrates forward into a greater or less portion of the orbicularis palpebrarum muscle, and anastomoses, by a considerable number of ramifications, with
the facial artery, which it meets, and with the infra-orbitar artery.
Sometimes this gives off all the upper part of the facial artery.
In some subjects its ascending minuscules extend much higher, and reach the outer extremity of the edge of the orbit.
The middle temporal artery ( A . temporalis media) generally arises some lines above the transverse facial artery, a little below the malar bone, a considerable branch, which proceeds first from below upward, gives off one or several minuscules to the upper part of the masseter muscle, then curves backward at a right angle, between the trunk and the temporal muscle, and terminates partly in small twigs, which penetrate into the substance of the muscle where they anastomose with those of the deep temporal artery, and partly in superficial branches, which are distributed on the auditory passage, where they communicate with those of the posterior auricular artery.
After giving off this artery, the trunk of the temporal artery goes upward and forward, on the temporal muscle, directly under the skin, and describes a considerable arch, which is convex posteriorly and terminates as the anterior temporal artery (Jl. temporalis anterior ), anastomosing several times with the superciliary artery, and giving branches to the frontalis muscle, and to the skin of the forehead.
Small inconstant branches come from the anterior and concave part of the arch which it describes, these go forward into the outer part of the orbicularis palpebrarum muscle, and communicate with the ascending branches of the transverse facial, and also with the upper minuscules of the anterior temporal artery.
The posterior branches of the superficial temporal artery are,
1st. The anterior inferior auricular arteries (Jl. auricular es anteriores inferiores ), usually three or four in number, which arise directly above one another from its lower part, and are expanded in the inferior and anterior part of the concha.
2d. The anterior and superior auricular artery {Jl. auricularis anterior superior) which is often single, rarely double ; it arises nearly opposite the preceding branches, and goes to the upper and anterior part of the concha, and to the attollens auriculae muscle.
Mayer describes it as the tenth branch of the external carotid artery (p. 84), but asserts positively that it arises about a line above the internal maxillary artery. The descriptions of Portal (p. 186), Boyer (p. 42), Bichat (p. 152), and Menon (p. 267), agree, like that of Murray, with the results of our observations.
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3d. Two or three larger branches usually go backward, inward,
and upward, and anastomose with each other and with those of the
opposite side, and with the superficial occipital artery, which sometimes partly replaces them. They are called the posterior temporal
arteries ( A . temporales posteriores'), and they are usually wrongly considered as forming, in opposition to the anterior temporal artery, but
one branch.
II. INTERNAL MAXILLARY ARTERY.
§ 1359. The internal maxillary artery {A. maxillaris interna , A. orbito-maxillaris) is larger than the preceding, but differs more from the direction of the primitive trunk, and is situated more deeply, so that it cannot be seen entirely till the zygomatic arch and the outer part of the body of the upper maxillary bone is removed.
Its direction changes several times in its course. First, it goes transversely inward and a little forward, behind the neck of the jaw ; then it goes directly inward, and passes between the two pterygoidei muscles, or curves again a little forward. Arrived at the pterygoid process, it goes perpendicularly upward, over the pterygoideus extern us muscle, and is reflected on itself as high as the floor of the orbit, so that its direction becomes horizontal. Thence it divides into several branches which descend more or less, by which it terminates, distributing itself on one side on the inner and posterior part of the nose, on the other to the outer part of the face.
Proceeding in this manner, it distributes the blood to the dura mater, to the internal ear, to the pterygoidei muscles, to the temporalis muscle, to the teeth, to the interior part of the nose, to the upper part of the pharynx, and to a part of the face, and communicates with several branches of the external and internal carotid, by the following branches, which are successively given off. It usually sends one or two to the ear, viz :
a. The deep-seated auricular artery (A. auricidaris profunda), which goes to the organ of hearing.
b. The artery of the tympanum (A. tympanic a), which is distributed to the temporo-maxillary articulation, and then penetrates into the cavity of the tympanum, through the fissure of Glaser. These two branches often arise from the external carotid artery, or from the facial or temporal artery.
c. The small meningeal or the external pterygoid artery ( A.meningca parva, s. pterygoidea externa ) is an inconstant branch, which often arises from the middle meningeal or from a pterygoid artery ; it gives bmnches to the pterygoidei muscles, to the muscles of the soft palate, and to the dura mater, near the sella turcica, and sometimes penetrates into the skull through the foramen ovale.
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INSCRIPTIVE ANATOMY.
d. The middle , or great meningeal , or spheno-spinal artery (./?. méningée i media , s. magna , s. spmosa),(l) is the largest branch of the
internal maxillary artery.
It arises from the upper part of the origin of the internal maxillary artery. It goes directly upward and gives off branches to the pterygoid ei muscles, to the upper constrictor of the pharynx, to the temporal muscle, and to the muscles of the soft palate ; these are sometimes, although rarely, deficient. When they do not exist they are replaced by the small meningeal artery.
The artery then, either simple or divided, enters through the sphenooccipital hole of the sphenoid bone, into the skull, and then gives off some ramifications posteriorly, which glide into the fissure of Fallopius, penetrate into the cavity of the tympanum and the canal of the facial nerve, are distributed to the membrane of the tympanum, to these nerves, and to the muscles of the tympanum, and anastomose with the stylomastoid artery. Others, which are anterior, sometimes penetrate into the orbit, through the malar bone or the large wing of the sphenoid bone, and to the lachrymal gland. But this trunk, covered on the outer face of the dura mater, above which it projects, and of which it is the largest artery, expands principally in- the anterior and central part of this membrane. It arises, near the anterior edge of the parietal bone, at the median line of the skull, and gives off, forward and backward, numerous branches, which anastomose with the other branches of the middle, and also with those of the anterior and posterior meningœal arteries.
Besides, these branches communicate also with those of the temporal and occipital arteries.
As they project above the dura mater, and follow the grooves of the skull-bones, these indicate their course very well.
e. The inferior maxillary or inferior denial artery (A. maxillaris , s. alveolaris , s. dentalis inferior ), which sometimes arises from the middle meningceal artery, and always comes from the lower point of the origin of the internal maxillary artery, descends between the two pterygoidei muscles, to which it gives twigs, and also sometimes to the temporal muscle : penetrates into the dental canal, through which it passes forward, gives ramifications to all the teeth and to all the lower dental nerves, which occupy the same canals as they do, then emerges from the mental foramen, and anastomoses above with the inferior coronary or labial, and below with the submental artery, and produced, like the preceding, by the facial artery.
(1) Some anatomists, as Sabatier, Boyer, and Bichat, state that it is the first branch of the internal maxillary artery. We have always seen it preceded by one or more of those we have mentioned, and we have never found it, as Mayer states, arising directly from the bifurcation of the external carotid artery. According to our observations, it does not normally arise before the inferior dentar artery, as SÅ“mmering, Murray, and Munroc assert. We have seen that Portal was correct in saying that it is given off as frequently after it. or at least opposite to it.
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This emerging branch most commonly arises at some distance from
the mental foramen, within the dental canal, and on a level with the
small malar teeth, at the place where the inferior maxillary artery
bifurcates to produce it and the continuation of the trunk.
f g. Two or more cleep-seated temporal branches {ll. temporalis profundi ) arise from the upper part of the maxillary, and are distributed to the buccinator and the pterygoidei muscles, and especially to the temporal muscle ; penetrate also into the orbit, where they send branches into the lachrymal gland and the eyelids, and anastomose extensively with the ophthalmic artery.
h. The masseter artery ( R . massetericus) is not constant, and arises sometimes from the external temporal, or even the external carotid, or finally from one of the deep pterygoid arteries. It passes over the semicircular notch of the lower jaw into the upper part of the masseter muscle. It gives branches also to the temporal muscle, and to the two pterygoidei muscles, especially to the external.
i. The buccal artery {Ji. buccalis, s. buccinatoria ) is a very constant branch, although it often arises from the deep temporal artery, or from one of the following branches. It comes from the lower part of the inferior maxillary artery, goes downward and forward, along the outer face of the body of the upper jaw, distributes its branches in the buccinator muscles, the muscles of the upper lip, the lower part of the orbicularis palpebrarum muscle, the buccal membrane, sometimes also the anterior teeth to which it comes by several openings which exist in the upper part of the superior maxillary bone, and anastomoses with the branches of the facial, and also with those of the infra-orbital, artery.
k. The superior maxillary or alveolar artery {A. maxillaris superior, s. alveolaris) arises sometimes from one of the deep temporal or from the infra-orbital arterju It is larger than the preceding, goes a little downward and forward, turns on the upper maxillary bone, and sends off numerous large and small branches, one of which is termed the superior dental artery {E. dentalis superior ) into the teeth of the upper jaw. These branches nourish the dental capsules, the periosteum, the germ, the buccinator muscle, the zygonraticus major muscle, and anastomose with the branches of the facial and infra-orbital arteries.
l. The infra-orbital artery {A. infra-orbitalis) is generally smaller than the preceding, and arises near the bottom of the orbit. It soon engages itself in the infra-orbital foramen, and the infra-orbital canal, sends some branches into the orbit and the maxillary sinus, emerges by the infra-orbital foramen, behind the levator labii superioris, thus comes on the front of the face, and terminates in a great many ramuscules, some of which go to the muscles of the upper lip, while the others anastomose with the upper dental artery, the dorsal artery of the nose, the orbitar and the palatine artery.
Finally, at the upper end of the zygomatic fossa, the internal maxillary artery divides into an ascending and a descending branch, which goes inward.
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DESCRIPTIVE ANATOMY.
m. The superior palatine artery ( A.palatina suprema , s. descendens,
s. pterygo-palatina ) gives off, first, the superior or descending pharyngeal
artery (A. pharyngœa suprema , s. descendens). This passes through the
pterygo-palatine foramen, and expands in the pterygoid process of the
bone, and the Eustachian tube and the upper part of the pharynx. Sometimes it arises from the internal maxillary artery by a distinct trunk.
The superior palatine artery descends in the pterygoid canal and
divides into several minuscules, which pass through different openings,
to go to the soft parts of the palate. The trunk passes through the
posterior palatine canal, comes on the palatine arch, rests directly on
its lower face, describes a right angle to go forward, forming numerous
curves, in its course gives off twigs to the mucous membrane of the
palate and to the muciparous glands, and anastomoses forward with
that of the opposite side, and sends its latter branches through the
anterior palatine foramen into the nasal cavity, where they extend to
the lower turbinated bone, communicating with the branches of the
artery of the septum and of that of the dorsum of the nose which arise
from the facial artery.
n. The last branch, the posterior nasal or sphenopalatine artery (A. nasalis posterior, s. splieno-palatina ), enters through the sphenopalatine hole into the posterior part of the nasal fossa, and divides into two branches, an external and an internal, and sometimes into three.
The internal branch, the posterior artery of the septum of the nose ( A . septi narimn posterior ), descends along the posterior pare of the septum of the nose, sends minuscules to the upper part of the pharynx, and penetrates into the posterior cellules of the ethmoid bone, and also into the upper turbinated bone.
The external branch descends along the outer edge of the posterior opening of the nasal fossae, and usually divides into two ramuscules, which go, the upper to the middle, and the lower to the lower turbinated bone. These ramuscules are distributed principally in the posterior part of the nasal fossa and of the maxillary sinus.
II. INTERNAL CAROTID ARTERY.
§ 1360. The internal carotid or anterior cerebral artery (A. carotis interna , s. cerebralis, s. cerebralis anterior , s. encephalica ) is usually smaller than the external, ascends behind it, before the internal jugular vein, on the outside of the pneu mo-gastric nerve, directly before the vertebral column, to the lower orifice of the carotid canal. It does not generally bend much, although it is sometimes very tortuous, and it is rarely straight.
It seldom gives off branches in this course. It rarely in fact furnishes one of the internal or posterior branches of the external carotid or of the occipital artery. The latter comes from them less frequently than the others. Upward it gives off sometimes a small branch, which goes to the palatine region and to the velum palati.
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247
Immediately below its entrance into the carotid canal it is generally
almost horizontal, or at least goes obliquely upward and forward. At
the lower part of this canal it goes vertically upward. It afterwards
goes forward at nearly a right angle, and becomes almost horizontal,
although it ascends a little. After leaving the canal it resumes its primitive direction upward, but proeeeds at the same time forward and
inward, and thus comes on the side of the sella turcica. At the posterior part of this excavation it curves a second time at a right angle,
goes horizontally in the lateral carotid groove, going outward and a
little downward. In this part of its course it accompanies the cavernous sinus of the dura mater, both being inclosed in the same portion of the dura mater, but separated by its proper membrane from the
blood which it contains. At the anterior extremity of the lateral face
of the sella turcica, below the anterior clinoid process, it describes a thud
right angle, and goes upward, backward, and inward. In its course it
gives off very trifling branches to the internal ear, to the dura mater,
and to the third, fourth, fifth, and sixth pairs of nerves. Opposite the
internal extremity of the upper orbitar fissure it divides into two branches,
the continuation of the trunk which goes to the brain, and the ophthalmic artery.
Thus it changes its direction five times at least, and this arrangement retards the course of the blood much more, inasmuch as all the curves are sudden and do not occur on the same plane.
The internal carotid artery is intimately united by a very short cellular tissue to the canal through which it passes and which it almost entirely fills.
I. OPHTHALMIC ARTERY.
§ 1361. The ophthalmic artery (JL, ophthalmica ) is a very considerable branch, which exceeds in volume all those hitherto mentioned. It is always single. It leaves the skull through the optic foramen, usually on the outer and lower side, rarely at the upper part of the optic nerve, penetrates into the orbit, sends numerous branches to all parts of the eye, and also larger or smaller branches into the nasal fossæ and the face.
Having come into the cavity of the orbit, it soon ascends on the optic nerve, goes upward and inward, passes between this nerve and the rectus superior muscle of the eye, and thus arrives at the inner part of the orbit and goes forward to the internal angle of the eye.
Its branches vary surprisingly in respect to their origins, their number, and their volume. The principal are :
1st. Usually but not always an external posterior ciliary artery {A. ciliaris posterior), which arises from the outer side of the ophthalmic artery, goes forward along the optic nerve on its outer and lower side, and penetrates the sclerotica directly before the anterior extremity of this nerve.
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DESCRIPTIVE ANATOMY.
2d. The lacrymal artery (A. lacrymalis) arises from the upper part
of the ophthalmic artery, generally far backward and sometimes very
far forward. It rarely arises from the middle meningeal artery, in
which case it enters into the orbit, through the upper orbicular fissure,
or through a special opening either in the malar bone or in the large
wing of the sphenoid bone. It proceeds outwardly under the rectus
superior muscle, to which it gives branches, and also to the rectus externus and to the levator palpebrarum muscles. It sometimes sends
several through the malar bone into the temporal muscle, where they
anastomose with those of the deep temporal artery. In some subjects
one or several ciliary arteries arise from it. It then passes across,
above or below the lacrymal gland, leaves the orbit at the external
angle of the eye, anastomoses with the palpebral artery given off by
the ophthalmic artery to form the palpebral arch, and terminates in
the orbicularis palpebrarum muscle, the skin of the eyelids, and the
tunica conjunctiva.
3d. The posterior upper ciliary artery (A. ciliaris posterior, superior ) is distributed in the same manner as the external, but gives off no branch after passing through the tunica sclerotica. Sometimes all the posterior ciliary arteries arise after the posterior ethmoidal artery ; but they always proceed very tortuously on the surface of the optic nerve, and after dividing into numerous branches, pass through the posterior part of the sclerotica to enter the eye, where they are distibuted in the manner stated in describing that organ.
4th. Next, a small inconstant branch arises and goes to the posterior part of the rectus superior muscle.
5th. The posterior or middle ethmoidal artery (A. ethmoidalis posterior , s. media) is also inconstant, and often arises from the lacrymal artery, from the anterior ethmoidal, or from the supra-orbitar artery.(l)
It gives first branches to the origin of the obliquus superior, rectus internus and externus muscles, then goes inward over the obliquus superior muscle, passes through the ethmoidal . or posterior internal orbital - foramen, comes into the nasal fossæ, and is distributed to the posterior ethmoidal cellules, the sphenoidal sinus, and the antrum Highmorianum ; it anastomoses with the branches of the posterior nasal or spheno-palatine artery and with the anterior ethmoidal artery, then reenters the skull through a small canal in the ethmoid bone, gives ramuscules to the periosteum which covers the anterior and central fossa of the base of the skull, and terminates by again passing into the nasal fossæ through the openings in the cribriform plate.
6th. The central artery of the retina (A. centralis retinae ), arises farther back, directly from the ophthalmic artery, or from the preceding, or from the lacrymal urtery, or from one of the two muscular branches ;
(1) But it is not always the smallest, as Bichat asserts ; we have remarked several times that it was one of the largest branches and much larger than the anterior.
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249
it goes into the optic nerve, proceeds forward along ils axis, and distributes itself to the retina, as we shall meniion in describing the eye.
7th. The inferior muscular artery (A. muscularis inferior ), is a considerable and rather constant branch, which sometimes gives off the central artery of the retina and one or more of the ciliary arteries, goes inward, sends branches to the rectus interims and inferior muscles of the eye, and penetrates even into the nasal fossæ.
8th. The superior muscular or supra-orbitar artery {A, muscularis superior , s. supra-orbitaria) is less constant than the preceding, but it comes from the lachrymal less frequently than from the ophthalmic artery. It proceeds forward directly below the orbitar plate, leaves the orbit through the supra-orbitar foramen, gives off branches to the frontal bone, to its periosteum, to the supraciliaris and orbicularis palpebrarum muscles, and to the skin of the forehead, and anastomoses with the other branches of the ophthalmic and with the temporal artery.
The anterior ciliary arteries (A. ciliares anticœ ) arise from this branch and from the preceding ; they divide into fewer branches than the posterior, and enter the sclerotica much farther forward than the latter, near the transparent cornea.
The branches we have described generally arise near the floor of the orbit, not far from each other ; hence why they are generally long. After giving them off, the ophthalmic artery is usually smaller and proceeds along the- internal wall of the orbit, describing numerous curves. Towards the anterior opening of the orbitar cavity it gives off,
9th. The anterior ethmoidal artery (A. elhmoidalis anterior), which goes directly inward, passing over the obiiquus superior muscle, and penetrates through the ethmoidal or anterior internal orbitar foramen into the nasal cavity, where it is distributed to the anterior ethmoidal cells and the frontal sinuses, and anastomoses with the other nasal arteries. It also sends off branches to the anterior region of the dura mater.
The ophthalmic artery now proceeds a short distance within the orbit, afterwards leaves this cavity at the inner angle of the eye, and terminates in giving origin to,
10th. The paljiebral arteries (A. palpébrales]. These arise sometimes by a common trunk ( palpebralis communis) and sometimes separately, the superior a little before the inferior, and go outwardly. They are distributed partly to the conjunctiva, partly and particularly to the eyelids, in which they disappear between the skin and the orbicularis muscle. They divide there principally into two branches, one of which proceeds near the edge ( ramus marginalis) , while the other goes obliquely outward along the base of the eyelid.
The superior palpebral artery anastomoses in this place with the lachrymal, the superciliary branch of the frontal, and even some branches of the anterior temporal artery. It also forms a single or double superior palpebral arch ( arcus tarseus superior), which communicate with each other by numerous ramuscules, and thus form a net-work.
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DESCRIPTIVE ANATOMY.
The inferior palpebral arch ( arcus larseus inferior) is produced in the
same manner, by the anastomosis of the inferior palpebral with the
infra-orbitar, the lachrymal and the nasal arteries.
All the parts of the eyelids are abundantly provided with vessels by these arterial branches.
11th. The frontal artery (A. frontalis ), which also ascends soon after arising, usually divides immediately into three branches, the supraciliary artery ( A, supraciliaris ), the superficial or subcutaneous frontal artery (A. frontalis subcutanea), and the deep frontal artery (A. frontalis profunda) . By this division it is distributed, 1st, to the upper part of the orbicularis palpebrarum and corrugator supercilii muscles ; 2d, to the frontalis muscle and to the skin of the forehead ; 3d, to the frontal sinus. It extends to the coronal suture and to the temporal region, where it anastomoses with the branches of the external temporal artery; it also communicates in other parts with those of the supra-orbitar and lachrymal arteries.
12th. The nasal artery {A. nasalis) varies much in volume. Sometimes it is a very small branch, terminating at the root of the nose ; sometimes it forms the continuation of the trunk of the ophthalmic artery, descends very low, contributes with the lateral nasal branch of the facial artery to produce the dorsal artery of the nose, extends to the end of the nose, proceeding on the side of this organ, always anastomoses with the inferior palpebral and the facial artery, and gives ramuscules to the integuments and to the nasal bones, to the frontalis muscle, to the internal part of the orbicularis palpebrarum, to the muscles of the nose, and even to the pituitary membrane.
II. CEREDRAL ARTERIES.
§ 1362. After giving off the ophthalmic artery, the internal carotid artery is distributed entirely to the cerebrum, particularly to its anterior portion, the posterior being supplied with blood from the vertebral artery. It properly deserves then to be called, from this point, the anterior cerebral artery (A. cerebralis anterior).
<§ 1363. It gives off, first, small ramuscules, which go inward, and are designed for the posterior part of the optic nerve, for the infundibulum, for the pituitary gland, and for the third ventricle.
§ 1364. It then gives off four branches ; these are the communicating artery, the choroid artery, the anterior cerebral artery, and the artery of the corpus callosum. The first two generally arise directly after each other ; and the carotid artery bifurcates farther on to give rise to the last two. Sometimes, but more rarely, three or all of these branches arise from the same point.
§ 1365. The first, or the posterior communicating artery (A. communicans posterior), goes backward and inward. It approaches that of the opposite side, opens into the posterior cerebral, which comes from the vertebral, artery, or if we prefer it anastomoses with a branch analogous to it, which it meets.
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251
This anastomosis gives rise to the posterior part of the circle oj
Willis ( circulus Willissii).
The size of this communicating artery varies extremely. It is generally considerable, and only about one half smaller than one of the succeeding branches, into which the internal carotid artery divides. It is sometimes however very small ; in this case the anastomosis between the internal carotid and the vertebral artery, frequently but not always takes place by means of another and larger branch of the anterior cerebral artery, which opens more outward into the posterior. The communicating artery is sometimes larger on one side than on the other.
Sometimes this artery is a branch of the anterior cerebral.(l) It arises more rarely not from this but directly from the basilar artery, when the posterior cerebral artery does not come from it. and it is given off by the internal carotid.
But the anastomosis almost always exists ; and it is constantly simple or at most double, on each side, when it occurs by considerable branches, although we find others which are accessory and smaller in the cerebral peduncles.
We consider its total absence as one of the rarest anomalies. We have never yet seen it, and Barclay alone mentions one case where the injection penetrated neither from the carotid into the vertebral artery, nor from the vertebral into the carotid.(2)
Several vessels arise from the communicating artery and go to the pia-mater or to the floor of the third ventricle, to the mamillary eminences, to the posterior part of the optic nerves, to the thalami optici, to the cerebral peduncles, to the inner face of the anterior part of the large cerebral lobe, and to the choroid plexuses.
§ 1366. b. Above the communicating artery, the internal carotid always gives off a special branch, the choroid artery (A. ckoroidta) which also arises from its posterior part. (3) This artery goes a little backward and outward, along the posterior edge of the origin of the optic nerve, ascends above the upper part of the cerebral peduncle, and expands partly in the pia-mater of the anterior part of the posterior
(1) This anomaly, however, is proportionally very rare. Portal then estimates incorrectly, the relation between the rule and the exception, in saying' that the internal
carotid artery usually divides into two branches, the smaller of which is the artery of
the corpus callosum, the larger the anterior lobate artery; the latter givingoffthe
communicating artery, which sometimes arises directly from the internal carotid.
Hilderbrandt seems to think that the two cases are equally frequent, which is just as
false.
(2) hoc. cit., p. 47.
(3) We have always found this branch very constant, although several anatomists particularly Mayer, Murray, Portal, Hilderbrandt, and SÅ“mmerring, do not mention it. Haller states (le. anat., vol. vii. p. 5) that it sometimes exists. Sabatier, Boyer, and Bichat assert that is constant , which agrees with our remark. But Bichat errs in saying thatthe choroid is always smaller than the communicating artery. This case frequently occurs, since, as we have observed, the communicating artery is usually large ; but we have often found, when this was small, that the choroid artery was as large or even larger than it.
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252
cerebral lobe anil of the thalami optici, and partly also penetrates through the anterior opening of the lateral ventricle, into this cavity, where its ramifications expand in the choroid plexus.
§ 1367. The internal carotid now divides, at a very obtuse angle and at the anterior extremity of the fissure of Sylvius, into two unequal branches ; these are the artery of the corpus callosum and the anterior cerebral artery.
§ 136S. The artery of the corpus callosum ( A . callosa, s. corporis callosi, s. anterior cerebrica , s. anterior hemisphœri, s. mesolobica ) is always smaller than the posterior branch. It goes forward and inward, directly before the union of the optic nerves, proceeds to meet that of the opposite side, towards which it converges very much, and after giving off superiorly generally several ramuscules for the posterior extremity of the anterior lobe, for the olfactory and for the optic nerves, it anastomoses with it between the posterior extremities of the first two lobes by the anterior communicating artery (A. anterior communicans , s. anostomotica). This branch is generally very short ; sometimes however, it is three or four lines long ; it is generally much larger in the former case and often very narrow in the second. Its direction is always transverse. Sometimes it is entirely double; and we not unfreqüently find it, double in one half its extent.(l) It gives off, particularly when longer than usual, ramuscules, which go upward and backward, into the septum lucidum, the fornix, and the corpus callosum.
The trunk also generally sends off one or more small branches which proceed forward and outward to the inner part of the inferior face of the anterior lobe of the cerebrum. After this, it is situated directly near that of the opposite side, turns on the anterior extremity of the corpus callosum, ascends to the inner face of the cerebral hemispheres, and divides into several branches, the anterior of which enter into the circumvolutions of this internal face, while the posterior proceed on the corpus callosum, as far as its posterior extremity, where they begin to change their direction and to go upward. All these branches extend to the upper face of the cerebrum and anastomose with those of the succeeding artery, and with those of the posterior cerebral artery, given off by the vertebral artery.
Besides these large branches, into which the artery of the corpus callosum divides above, it also gives off, from its lower and concave part, numerous smaller branches, whtch distribute themselves in the corpus callosum.
Rarely, a large posterior branch is detached on both sides at the place where the two arteries of the corpus callosum meet, and the anterior anastomosing branch becomes the single trunk of the anterior part of the artery of the corpus callosum, which shortly divides into two large branches, a right and a left, or the two arteries arise
(1) Bichat is incorrect in stating that this arrangement is very rare.
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from a common trunk, and do not give oft a branch posteriorly. This
arrangement is remarkable because of the analogy it establishes with
the union of the two vertebral arteries into one, the basilar, which is
situated on the median line.
§ 1369. The anterior or more properly the middle cerebral artery (A. cerebri anterior, s. media , s. hemisphcerica media, s.fossœ Sylvii, s. sylviana), the last and the most posterior branch of the internal carotid, is always much larger than the preceding. Soon after its origin it goes outward, and only a little inward ; it enters the fissure of Sylvius, gives off, at its upper and posterior part, numerous, generally small, ramuscules, some of which penetrate into the anterior extremity of the posterior lobe, others into the posterior extremity of the anterior lobe, and afterward divides generally about half an inch from its origin into two, three, or four large branches. The largest of the latter are turned backward, soon bifurcate, and proceed, closely against each other, into the bottom of the fissure of Sylvius, where they go upward and backward. The anterior attain the posterior and external part of the anterior lobe, and the posterior the anterior central part of the posterior lobe, gliding in the circumvolutions of the posterior face of the first and the anterior face of-the second, but penetrating mostly into their substance, through their outer face, and thus extend to the upper edges of the hemispheres, where they anastomose with the ascending branches of the anterior and posterior cerebral arteries.
§ 1370. The anterior and middle cerebral arteries are not always arranged symmetrically. The two large middle arteries not unfrequently arise (as Haller states and as we have verified) from the right carotid only, and the anterior, which is smaller, from the left carotid, an arrangement which deserves to be remarked as indicating the predominance of the right side over the left.
Sometimes also only the left anterior artery comes from the internal carotid of the same side, and the other three come from the right. We have seen this anomaly in several subjects.
If we add the union of the arteries of the corpus callosum at their origin, which we mentioned above, we here find a remarkable repetition of several of the varieties to which the origins of the trunks coming from the arch of the aorta are subject.
ARTICLE FOURTH.
ARTERIES OF THE UPPER EXTREMITIES.
§ 1371. The arteries of the upper extremities, for which we cannot find a better term than that of the brachial arteries(l) ( J1 . brachiales),
(1) This term is generally applied only to that portion of the artery which corresponds to the arm, and which might more properly be termed the humeral artery.
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DESCRIPTIVE ANATOMY.
arise on each side by a single trunk, generally called the subclavian
arteiy (A. subclavia).
I. SUBCLAVIAN ARTERY.
§ 1372. The two subclavian arteries {A. subclavia) arise from the ascending aorta, and extend to the scaleni muscles. They differ in their mode of origin ; for the left subclavian artery arises directly from the arch of the aorta, while the right proceeds indirectly from it, as it is the external branch of the trunk of the innominata ( truncus communis innominatas), which bifurcates and gives origin to it and to the right primitive carotid.
This at least is the most common arrangement. Sometimes, but rarely, the subclavian arteries arise directly from the arch of the aorta. We may there find two principal differences. Sometimes in fact the trunk of the innominata gives off the right subclavian and the carotid, the subclavian artery arising on the right, outside of the carotid, which is the least but also the rarest anomaly. Sometimes the right subclavian artery arises more to the left, until it is the extreme left trunk of those which arise from the arch of the aorta, below the left subclavian artery, and goes to the right, towards the corresponding limb, passing behind the other trunks, rarely directly, more frequently between the trachea and the esophagus, and still more frequently between the esophagus and the vertebral column.
§ 1373. The first branches of the subclavian artery are never constant. They often and in fact almost always arise from its upper extremity, directly before its passage between the scaleni muscles. But sometimes the artery gives off much sooner, and even near its origin, considerable branches, which go to the thymus gland, to the upper part of the pericardium, also to the trachea, to the bronchiæ, and to the esophagus (A. thymicœ, pericardiacee superior , anterior et posterior , broncliicœ, œsophagece, broncho-œsophagece), but they rarely or never belong to these parts alone, although they distribute branches to all. Even when these branches arise from the subclavian artery (which occurs on the left side more frequently than on the right, because it descends deeper) its course is no shorter, but it gives off no branch until just before passing between the scaleni muscles. Here, however, several large branches arise from it. These may be distinguished generally speaking into the upper or posterior and the lower or anterior branches ; and they vary much, for, 1st, the same twigs do not always arise from the same branches, so that the latter are not always of the same caliber ; 2d, small branches sometimes arise from the subclavian artery, by a common trunk, whence their number varies : 3d, they do not always emerge from the same point of the subclavian artery, the inferior arising sometimes farther forward, and the superior farther backward than usual.
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A. UPPER POSTERIOR BRANCHES.
§ 1374. The most constant of the upper and posterior branches are two, the vertebral artery and the inferior thyroid artery.
I, VERTEBRAL ARTERY.
§ 1375. The vertebral artery (v3. vertebralis ) is generally the first and largest of the two upper branches of the subclavian artery. Shortly after arising, it enters the arterial canal of the cervical vertebrae, and goes from below upward. This artery shows a great disposition to change its origin, and to arise directly from the arch of the aorta. We shall remark, 1st, that this anomaly, however common it may be, is seldom seen on the right side (at least to our knowledge), and that it rests always on the left ;( 1 ) 2d, that when it occurs, the vertebral artery is almost always inserted between the left carotid and the left subclavian arteries. If this branch arises directly from the arch of the aorta more frequently than the others, it may be attributed, we think, to the following facts : 1st, in the normal state it is the first branch of of the subclavian artery ; 2d, the vertebral vein normally empties itself into the common trunk of the subclavian and jugular veins. The other fact, that the anomaly appears almost entirely on the left side, seems to us to depend on this, that the division of the trunk into branches characterizes the left side of the ascending aorta even in the normal state, since the subclavian arteries there arise separately, and are not blended in a single trunk, as on the right side. The greater length of the left trunk of the innominata vein may contribute to it, since this anomaly should be considered, as we have remarked, an imitation of the arrangement of the venous system. Finally, the situation of this artery between the left carotid and the left subclavian arteries probably depends on its arising, in the normal state, from the internal and posterior side of the subclavian artery.
We sometimes but rarely find on the right side a similar anomaly where the vertebral artery arises from the bifurcation of the trunk of the innominata ; this is still more curious, because in comparing this arrangement with that on the left side we have a new proof that the anomaly does not destroy in the two sides the character of the normal type.
We know of only one case where the right vertebral artery arose from the arch of the aorta ; but that of the left side also presented the same anomaly.
(1) This might be easily proved by numerous quotations. Of all the authors who mention this variety Mayer is the only one who asserts the contrary; for, without speaking of the left vertebral artery, he asserts only that the right sometimes arises directly from the arch of the aorta. This assertion is so cont radictory to observation that it can be explained only by considering it as a typographical error.
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DESCRIPTIVE ANATOMY.
A second anomaly of the vertebral artery consists in its division into
several trunks. Sometimes then one of the trunks arises directly from
the arch of the aorta ; the other, which is generally smaller, from its
usual place ;(1) or both come from the subclavian artery, at. a greater
or less distance from each other. Perhaps the first arrangement also
is found only on the left side ; at least in a specimen before us, and
where the anomaly exists on the right, the two vertebral arteries are
branches of the subclavian artery. In both cases one of the trunks,
particularly the largest, enters the vertebral canal higher than usual.
Sometimes it unites with the other, which enters at the normal place ;
sometimes it unites with it before entering this canal ; sometimes, finally,
the smallest branch extends into the veitebral canal after passing over
one or more vertebral foramina.
Even when the vertebral artery is normal in respect to its origin, it enters the vertebral canal at several different points. Its proper place is the vertebral foramen of the sixth cervical vertebra. (2) In extremely rare cases this artery enters through the vertebral foramen of the seventh cervical vertebra.(3) Even when it arises lower than usual, from the arch of the aorta it however enters into the hole of the sixth cervical vertebra, and we have frequently seen it in this case not enter the vertebral canal until it reaches the fifth vertebra.
More frequently, although not very often, the vertebral artery, even if not double, enters through the vertebral foramen of the fifth, fourth, third, or even the second cervical vertebra. We know of no case in which it has been found entirely out of the vertebral canal, and we have never known it to leave this channel lower than the upper vertebra, or to leave a vertebra, pass through a certain extent on the anterior face of the transverse processes, and enter again into the vertebral canal.
Finally, the vertebral artery of one side is very frequently much larger than that of the other, although according to our observations the sides of the body have no effect on this disproportion.
This anomaly confirms the general rule that the synonymous arteries which go to the single organs on the median line of the body often differ in volume and enlarge on one side at the expense of the other.
(1) Henkel, Anmerkungen von weidernatürlichen Geburten , zweite Sammlung, p. 10, 11. — Huber, Dc arcus aortce ramis ; in the Act. Helv., vol. viii. p. 68-102.
(2) We have always observed this, except in a very few instances. Haller (/c. anat.fasc. ii., e.vplic. icon. 2, art. thyr. infer., not. c) and Scemmerring (p. 177) are then correct in saying that this arrangement is normal. Mayer mistakes in saying (p. 110) that there is for the vertebral artery a special opening, through which it enters into the vertebral canal, sometimes in the seventh and sometimes only in the sixth cervical vertebra. This opening always exists except in a very few instances in the seventh cervical vertebra ; but the vertebral artery rarely or never passes through it and always enters through the sixth. What Mayer considers the normal state is a rare anomaly, and vice versa. Monro ( Outlines , <f-c., vol. iii, p. 301) is also mistaken in thinking that the artery enters through the seventh cervical vertebra as often as it does through (he sixth.
(3) Bichat (p. 193) is correct in saying that it sometimes but rarely enters through a similar foramen of the seventh cervical vertebra. This arrangement is rare, as Haller, Murray, and Scemmerring have not spoken of it, although they mention the next.
ANGEIOLOGY.
257
§ 1376. The vertebral artery ascends in an almost straight line to the
second cervical vertebra ; but at this point it becomes tortuous and describes several curves, four of which are very remarkable. First, it
penetrates into that part of the canal which belongs to the transverse
process of the second vertebra, forming a right angle, assuming an entirely horizontal direction, and going transversely outward ; then passing through this opening, it describes another right, acute, or obtuse
angle, resumes its first direction, and becomes perpendicular again at
the upper cervical vertebra. When it has passed through the vertebral
foramen it inclines again at a right angle, resumes a second time a
horizontal direction, and goes backward and inward, turning around
on the articular process of the first Cervical vertebra, along its posterior
groove. From the posterior extremity of the articular process it goes
gradually and at an obtuse angle inward and upward, and soon enters
the cranium, passing through the dura mater and the large occipital
foramen directly above the occipital condyle. Having entered the
skull, it is situated first on the side, then on the lower face of the medulla oblongata, and ascends forward and inward on the basilar process of the occipital bone. There the two arteries approach each other,
and after passing usually more than an inch within the cavity of the
skull, they unite at an acute angle, either a short distance behind the
posterior edge of the pons Varolii, or on this edge, or even in its centre.
They always, as far as we know, unite and give origin to a single
trunk, the basilar artery (A. basilaris ), which is much smaller than the
two branches which produce it. In size it nearly equals the internal
carotid artery after it gives off the ophthalmic artery. It proceeds forward to the centre of the lower face of the pons Varolii, and divides a£
its anterior extremity into two large branches, a right and a left.
§ 1377. In this course the vertebral artery generally gives off no branches, or at least but small and inconstant ones. These- branches are' distributed to the anterior deep muscles of the neck. In this respect the vertebral artery resembles the internal carotid.
§ 1378. From the portion within the vertebral canal several small branches pass forward, outward, and backward, generally between every two vertebrae, and go to the vertebrae, to the intertransversarii, to the multifid us spinæ, to the anterior deep muscles of the neck, and to the small muscles of the head.
Internal branches, which are also very small, pass through the intervertebral foramina, either alone or attended with small arterial twigs from the other branches of the subclavian artery, penetrate the vertebral canal and are distributed partly to the nerves, others to the anterior and posterior sides of the dura mater and to the pia mater of the spinal marrow. They anastomose with those of the opposite side and with the anterior and posterior spinal arteries.
Considerable branches arise- from that part of the vertebral artdry between the first and the second cervical vertebrae, and also between tire Vol. II m
DE S C Rir T I VE A N A T 051 V
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latter and the occipital bone. Some go outward, are expanded in the transversales colli and the coinplexus minor muscles, and anastomose with the branches of the ascending cervical artery, and sometimes entirely replace it. The others proceed backward and outward and are distributed in the posterior and lateral small muscles of the head. Some go inward and anastomose with the synonymous branches of the other side. Finally, man}' enter the tissue of the dura mater.
§ 1379. The largest branches arise from that part of the vertebral artery within the skull. From the difference of caliber between the branches which it sends out of the cavity of the skull, this part is frequently much larger on one side than on the other, although both have primarily the same diameter at their origin and although the side of the body has no necessary influence upon this difference.
The branches which arise before the two vertebral arteries unite are the anterior spinal artery, the posterior spinal artery, and the inferior artery of the cerebellum.
§ 1380. The posterior spinal artery (A. spinalis posterior) is the smallest, and often comes from the inferior artery of the cerebellum. It arises the lowest and from the outside of the vertebral artery, goes inward on the posterior face of the spinal marrow, and descends on each side along the posterior spinal groove to the end of the spinal marrow. The two arteries are very tortuous and are parallel to each other. They are always enlarged by the accessory ramuscles of the vertebral, the deep cervical, and the intercostal arteries which pass through the intervertebral foramina, and anastomose by numerous transverse branches, which generally correspond to the intervertebral spaces ; so that each portion of the spinal marrow between two vertebrae has its special vascular circle, even as the four cerebral arteries form one by their anastomoses. •
§ 1381. The inferior artery of the cerebellum (,R. inferior cerebelli) a-lso arises from the outer side of the vertebral artery and is usually double on both sides.
One, the posterior inferior artery of the cerebellum, arises farther backward, and goes backward, upward, and inward, proceeds on the lateral parts of the medulla oblongata, distributes its branches to the tela choroidea of the cerebellum and to the floor of the fourth ventricle, and ascends between its two hemispheres to its vermiform eminence and to the inner face of its two hemispheres. This branch often exists on one side only, and then it is observed particularly when the inferior artery of the cerebellum arises very far forward.
The anterior inferior artery of the cerebellum sometimes arises at the origin, sometimes also at the extremity of that portion of the vertebral artery within the skull. In some subjects, particularly when the vertebral arteries unite early, it comes from the basilar artery. These varieties are observed even on both sides of the body at once. The anterior inferior artery of the cerebellum not only frequently exists alone but it is generally much larger than the posterior. It is some
ANGEIOLOGY
2Ô9
times much smaller on one side than on the other. It proceeds very
tortuously outward and backward to the lower face of the cerebellum.,
where impasses on the grooves which it crosses and divides into branches,
some of which go backward and others forward. These branches also
cross the direction of the grooves of the cerebellum ; the small ramifications alone become parallel and finally penetrate into them.
§ 1382. The anterior spinal artery (A. spinalis anterior) generally commences a short distance from the lower edge of the pons Varolii, even when the two vertebral arteries unite much higher than usual. It arises from the internal part of the trunk and soon unites with that of the opposite side in a single trunk on the median line, which descends along the anterior groove of the spinal marrow. Generally, particularly when the two vertebral arteries unite higher than usual, we find a small anterior and superior spinal artery, which is sometimes single and arises from the top of the angle of union, and sometimes double, which blends likewise with that of the opposite side, and which, proceeding also from above downward, soon anastomoses with the lower. The single trunk of the latter, which corresponds to the median line, is often divided in its course and thus forms considerable islands. Its upper part receives also from all or most of the intervertebral foramina considerable branches, which are given off by the vertebral or the other cervical arteries to the anterior face of the spinal marrow and anastomose with it. During its course, which is very tortuous, it sends off on each side numerous branches to the spinal marrow.
II. BASILAR ARTERY.
§ 1383. The basilar artery (A. basilaris, s. meso-ccp'halica) is comstant, and arises, proceeds, and varies in the manner mentioned above. We however sometimes remark in its arrangement a tendency to a want of union or to the separation of the vertebral arteries, since it forms islands, especially at its posterior part. This artery is however the only one in which we have observed this arrangement. It very soon divides into two parts, which almost immediately unite. We consider this anomaly as very rare, not only because we have never seen it but twice, but because it is not mentioned by the most correct angeiologists.(l) It is curious not only as an anomaly, but because it increases the analogy between the basilar and the anterior spinal arteries, which are already so similar. It is not unimportant to say, that in the two subjects which presented this unusual arrangement the anterior communicating artery of the two internal carotids presented analogous
(1) An arrangement has been figured by Heuermann ( Physiologic , vol. ii. tab. 8) where the two vertebral arteries were connected behind their union by a large trans'verse branch, to give rise to the basilar artery, which seems to have some relation with this anomaly ; but more probably it consisted only in the union of the anteriorspinal arteries, since the two 'vertebral arteries are not v-ct united behind this branch.
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DESCRIPTIVE ANATOMY
divisions. In the latter however this anomaly is much more common
than in the'basilar artery.
From both sides of the basilar artery numerous branches arise, generally at right but sometimes at angles slightly acute, backward, which vary much in number and volume and do not correspond perfectly on both sides. The smallest enter into the pons Varolii and the nerves which come from it ; the largest, even when the usual inferior arteries of the cerebellum do not exist, proceed even to the lower face of the cerebellum.
Some branches, the internal auditory arteries (A. auditives internez ), enter into the internal auditory foramen, expand in the labyrinth, and anastomose with the branches of the internal and of the external carotid arteries which enter into this organ.
§ 1384. At its anterior extremity, in the middle of the anterior edge of the pons Varolii, the basilar artery usually divides into four branches, two on each side, the superior artery of the cerebellum and the posterior cerebral artery.
§ 1385. The superior artery of the cerebellum (A. cerebelli superior) which is almost as large as the inferior, is rarely deficient on one side, in which case it is replaced by a branch of the following. It is more frequently double ; and then the vertebral artery divides into five branches, of which the two superior arteries of the cerebellum are situated very near each other : sometimes but much more rarely, it arises some lines behind the anterior extremity of the vertebral artery. It goes transversely outward and upward, directly behind the anterior edge of the pons Varolii, then proceeds a little backward, turns upon the pons Varolii to arrive at the anterior edge of the cerebellum., and divides into superficial and deep branches. The first proceed backward on the ridge of the cerebellum to its posterior edge, where they anastomose with the branches of the inferior artery of the cerebellum ; the others penetrate upward into the anterior lobes.
§ 1386. The two anterior branches, the posterior or deep cerebral arteries, Lobaires postérieures du cerveau , Ch. {A. cerebri posteriores , s. profundœ), are much larger than the superior arteries of the cerebellum. They arrive at an acute angle, separate much from each other, and go forward and outward. They usually give off near their origin and at their upper and external part several branches, some of which are considerable and go to the cerebral peduncles, to the thalami optici, to the tubercula quadrigemina, and to the valve of Vieussens. After proceeding a short distance they divide into two branches, the communicating artery and the continuation of the trunk.
The communicating artery is situated inward, and is smaller than the other. Its direction is outward and forward and it proceeds to meet the anastomosing branch of the internal carotid artery, with which it unites.
The continuation of the trunk of the posterior cerebral artery, which fa usually the smallest of the 4hree proper cérébral arteries, sometimes
ANGELO LOG"?.
261
aiises from the internal carotid artery, previous to its bifurcation, and
sometimes also from the union of the anastomosing branches given off
by the internal carotid and the vertebral arteries. It goes outward and
upward, before the third pair of the cerebral nerves, and turns on the
cerebral peduncle, to the lower face of which it gives some ramuscules,
which thus arrive at the thalami optici and the tubercula quadrigemina, penetrate into the third ventricle, and are distributed principally
to the choroid plexus. Finally, it goes on one side to the posterior part
of the cerebrum and of the corpus callosum, and also to the thalami
optici on the other, particularly to the lower face of the cerebral hemispheres. It anastomoses very frequently with the anterior or central
arteries and with the arteries of the corpus callosum, which arise from
the internal carotid artery.
§ 1387. The peculiarities presented by the arteries of the brain have been described before or will be mentioned when we speak of the encephalon.
II. INFERIOR THYROID ARTEEY.
§ 1388. The inferior thyroid artery (Jl. thyroidea inferior, s. sacro thyroidea, Barclay ) arises from the subclavian artery, more outward and forward than the vertebral artery, from which however it is not always the same distance. It most generally gives off the inferior thyroid branch and several twigs, which go to the muscles and to the slan of the neck, the back, and the shoulder.
This artery is large, particularly in the child, where it is equal to the subclavian or even the carotid artery. Its size however varies much, because that one or more branches which it commonly furnishes frequently arise from other trunks, but the arteries which generally come directly from the subclavian artery are rarely given off by it. This is true for instance of the internal mammary artery, and the former is true in regard to the branches which go to the muscles of the neck, shoulder, and back. Sometimes it goes only to the thyroid gland. In other cases it is uncommonly large, because it gives off not only the usual branches but also the internal mammary artery. In rare cases, on the contrary, it does not deserve its name, because it gives branches only to the muscles and the inferior thyroid arises from the common carotid artery, or does not exist as a separate vessel, but is blended with the superior thyroid artery. This anomaly is curious, as it is a repetition of the normal formation of most mammalia.
Another and somewhat similar anomaly is when the inferior thyroid artery is uncommonly small, either on one or both sides, and one or both of the superior thyroid arteries are larger in the same proportion, or finally when beside the two common thyroid arteries, there is also a third (Jl. thyroidea imu , s. Neubaueri), which arises lower down either from the arch of the aorta on the right of the left carotid or from the common trunk of the carotid and the Subclavian artery, when the
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IJES'CRirïXVE ANATOMY
anomaly occurs on the right side, or from the common trunk of tin
carotids of one side only, df finally from both sides at once, sometimes
higher and sometimes lower.
We must also mention here the rare anomaly where the inferior thyroid artery is totally deficient on one side, while on the other, in the usual place, particularly on the right, instead of the two inferior thyroid arteries, we have a common trunk, ( 1 ) which arises sometimes from the aorta and sometimes from its usual place. We have twice observed a case resembling this, where the inferior thyroid artery arose from the arch of the aorta, between the trunk of the innominata and the left carotid arteries.
III. SUPERIOR SCAPULAR ARTERY.
§ 1389. In most cases the inferior thyroid artery, immediately after arising, gives off the superior scapular artery (R. transversus scapulœ, s. scapularis transversa, s. scapularis superior , s. cervicalis superficialis ), which however sometimes arises from the subclavian artery, sometimes singly, and sometimes by a common trunk with the following. It goes transversely backward and outward behind, and a little above the clavicle between the scalenus anticus and the scalenus médius ; gives branches to the sterno-thyroideus,the sterno-hyoideus, the omohyoideus, the scaleni, the trapezius, and the supraspinatus muscles ; passes between the spine and the glenoid cavity of the scapula, and enters the infraspinalis fossa. There it divides into several branches, the smallest of which usually pass through the semicircular notch to the anterior face of the scapula and to the subscapularis muscle, while the largest are distributed on the posterior face of this bone, to which it gives one or more nutritious twigs, and terminates in the infraspinatus muscle. Another branch arises from this point and goes forward between the proper and common ligaments of the scapula, distributes itself in the articular capsule of the shoulder and to the upper and anterior jtart of the deltoides muscle, and anastomoses by several large branches with the anterior circumflex artery of the arm and with the great thoracic artery.
IV. TRANSVERSE CERVICAL ARTERY.
§ 1390. The transverse cervical artery (Jl. cervicalis superficialis, s. cervicalis transversa, s. colli transversa ), which is generally as large as the preceding, arises from the inferior thyroid artery, a little higher and at some distance from it outwardly ; it often arises directly from the subclavian artery. It goes transversely outward and backward. It is situated at first on the side of and a little behind the superior capsular artery, and it gives off in this course branches to the scaleni muscles.
(1) Burns, loc. cit., p. 331.
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and divides into two large branches on a level with the upper edge of
the shoulder. The ascending branch becomes the principal branch of
the trapezius and also sends some ramuscales to the levator scapulae muscle ; the other descends along the base of the scapula, between
the rhomboidei and the serratus magnus muscles, in which course it
gives off twigs to these muscles and also to the lower part of the trapezius muscle.
§ 1391. A little higher, one or more small branches ( R . thoracici ) arise very constantly from the inside of the inferior thyroid artery ; these go upward and inward to the lower part of the longus colli muscle, penetrate also the spinal canal through the intervertebral foramina, but go particularly to the trachea and to the esophagus. The latter are termed the bronchial and the esophagceal arteries (A. branchiales, œ sophageœ, s. broncho-œsophageœ) .
§ 1392. After passing through rather a long course upward without giving off any branch, the inferior thyroid artery divides into two branches, the ascending cervical artery, which is generally much smaller and goes upward and outward, and the thyroid artery, which may be considered as the proper continuation of the trunk.
V. ASCENDING CERVICAL ARTETE.
§ 1393. The ascending cervical or the superior dorsal artery (A. cervicalis ascendens, s. dorsalis supremo) is a very constant branch of the inferior thyroid artery and sometimes but rarely arises from the subclavian artery ; this happens particularly when the branches already described arise separately from the proper thyroid artery. Sometimes also it arises from the internal mammary artery. It ascends along the transverse processes of the cervical vertebrae, between the longus colli and the scaleni muscles. In its course it gives off backward, outward, and upward several considerable branches, which are distributed in the upper part of the trapezius, the levator scapulae; the serratus magnus, the se,rratus posticus, the scaleni, and the splenii muscles, and the skin of the neck : the trunk generally goes backward, below the transverse process of the third cervical vertebra, penetrates deeply between the transversalis colli and the complexus minor muscles, and having thus come upon the posterior face of the neck, it terminates in twe principal branches ; the smaller ascends behind the transverse processes of the cervical vertebrae, gives ramuscules to the complexus minor muscle and to the posterior small muscles of the head, anastomoses with the vertebral and occipital arteries, and finally penetrates into the spinal canal between the first and second cervical vertebrae, where it terminates in the dura mater. The other is larger and is the continuation of the trunk : it goes outward between the fasciculi of the complexus major muscle, and terminates in this muscle and in the digastrieus and the posterior muscles of the head .
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OESCRIPTIVB ANATOMY.
§ 1394. The thyroid branch (R. thyroideus) sometimes arises singly
from the subclavian artery, from the aorta, the innominata, or from the
common carotid artery. It is sometimes entirely deficient in some subjects, but is generally the largest branch of the inferior thyroid artery.
It is very tortuous and curves very much in ascending toward the
thyroid gland. It usually passes behind, sometimes but rarely before,
the primitive carotid, in order to arrive at this gland. Before reaching
it, it divides into several branches, which enter this organ principally
on its lower edge and lower face and anastomose with each other and
with those of the superior thyroid artery.
The thyroid branch also gives in its course smaller ramuscules to the longus colli muscle, to the pharynx, and particularly to the larynx. The latter is termed the inferior laryngeal artery (Jl. lanjngea inferior).
VI. LOWEST THYROID ARTERY.
§ 1395. Besides the branch described (§ 1364), another branch called the lowest thyroid artery (Jl. thyroidea ima ) arises, sometimes from the primitive carotid or from the innominata, from the arch of the aorta or from the subclavian artery, by a trunk in common with that of the opposite side.
This anomaly occurs on the right side more frequently than on the left ;( 1 ) we have never observed it on the latter side, although we have frequently seen it on the other. In one case only, where the origin of the inferior thyroid artery was abnormal, it did not arise from the left side of the arch of the aorta, but from the right side, between the innominata and the left carotid artery ; thence it passed before the trachea to go to the left side of the thyroid gland, while the origin and direction of the right was normal. This anomaly then seems properly to belong to the right side, even as the similar anomaly of the vertebral artery appears exclusively on the left side.
Finally, whether this abnormal artery forms a part or the whole of the inferior thyroid artery, whether it arises from the innominata, or from the arch of the aorta, or deeply from the primitive carotid artery, it always passes on the anterior face of the trachea to go to the thyroid gland, into which it enters from below upward. It cannot then escape being wounded in the operation of laryngotomy.
(1) We have found it nine times on the right. Hubert (toe. cit., p. 84) has seen the lowest thyroid artery arise four times from the common trunk, three times on the right and only once on the left side. Neubauer has also seen the right coming from the aorta (in Erdmann, Descrip, art. thyr. imee, Jena, 1772). Ramsay (Account of an unusual conformation of some muscles and vessels, in the Edinb. Med. and Surg\ Journ., vol. viii. p. 281-283, tab. 1, fig. 2) has found it arising from the innominata trunk. Loder has twice seen it arising from the aorta, between the right carotid and the subclavian arteries : the innominata trunk did not exist in these two cases (De nonnullis arteriarum varieUdibus, Jena, 1781).
ÀNGEIOLOGY.
265
VII. DEEP CERVICAL ARTERY.
§ 1396. The deep cervical artery (A. cervicalis profunda) often forms a special trunk, which arises from the back side of the subclavian artery, a little more externally than the preceding, but frequently by a common trunk with the superior intercostal artery. It is rarely given off by the inferior thyroid or even by the vertebral artery ; in the latter case its origin is generally a little below that of the vertebral artery. It more rarely comes from the upper part of the latter, in which case it sometimes descends between the first cervical vertebra and the occipital bone, and is afterwards distributed as usual, but so that its lower branches are almost always supplied by the other branches of the subclavian artery.
It goes obliquely upward and outward, passes backward between the transverse processes of the sixth and seventh cervical vertebrae or the latter and the first dorsal vertebra. It ascends between the transversale colli, the spinalis colli, and the semispinalis dorsi muscles on one side, and the digastricus and the complexus muscles on the other. It also distributes branches to the scaleni, the complexus minor, the cervicalis descendens, the trapezius, the splenii, and the small posterior muscles of the head, and anastomoses, especially above, near the occipital foramen, with the branches of the vertebral and occipital arteries. It also sends ramuscules into the spinal canal through the intervertebral foramina, which anastomose there with the spinal arteries given off by the vertebral artery.
B. INFERIOR BRANCHES.
§ 1397. The inferior branches of the subclavian artery are the internal mammary artery and the superior intercostal artery.
I. INTERNAL MAMMARY ARTERY.
§ 1398. The internal mammary artery (A. mammaria interna , s.
sternalis , s. substernalis) is much smaller than the vertebral and the
inferior thyroid arteries. It arises ordinarily and very constantly by a
-distinct trunk from the anterior or inferior side of the subclavian artery,
nearly opposite the inferior thyroid artery. It however in some rare
cases, one of which is now before us, arises by a common trunk with
the latter, or on the right side from the innominata,( 1 ) or even from
the arch of the aorta. (2)
It generally goes downward and inward, but sometimes also ascends a little before taking this direction, which it long preserves. It
(1) Neubauer, loc. cit., p. 33.
(2) Bcehmer, De quat. et quinq. aortæ ram.; in Haller, Collect, diss. anat.. vol. ii. p. 452.
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DESCRIPTIVE ANATOMY.
descends almost in a straight line to the posterior face of the anterior
wall of the chest, on the costal cartilages between the intercostales and
the triangularis sterni muscles, nearer its internal than its external extremity, consequently not far from the two edges of the sternum, which
it also approaches a little below.
Besides several branches which go from its upper part to the lower part of the anterior muscles of the neck, it sometimes gives off a superior bronchial artery, the thymic, and a branch which is distributed to the pericardium and also to the anterior mediastinum. But its upper part constantly gives off a branch which accompanies the diaphragmatic nerve, called the superior diaphragmatic artery (A. diaphragmatica superior , s. pericardio-diaphragmatica). This branch sends ramuscules to the pericardium, to the internal wall of the mediastinum, and to the esophagus, and expands in the anterior and middle portion of the diaphragm, where it anastomoses with the inferior diaphragmatic artery.
In its course along the sternum the internal mammary artery gives off external and internal branches.
The external branches, the anterior intercostal arteries, {A. intercostales anteriores ), are usually larger and more numerous than the internal. Their number is not exactly the same in every part, but they equal in number the intercostal spaces, over which the internal mammary artery passes. They generally proceed along the lower, rarely along the upper edge of the ribs, and almost always in the latter case one intercostal space contains two of them. They go backward between the intercostales interni and extern! muscles, and anastomose with the intercostal arteries given off by the descen
