Book - Handbook of Pathological Anatomy 2.6: Difference between revisions
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moiivcmens en rond, in the Mérn. de Paris, ÎV27, p. 25-33, — Vicq ci’Azyr, Œuvres, | moiivcmens en rond, in the Mérn. de Paris, ÎV27, p. 25-33, — Vicq ci’Azyr, Œuvres, | ||
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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.
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