Book - An Atlas of Topographical Anatomy 27

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Braune W. An atlas of topographical anatomy after plane sections of frozen bodies. (1877) Trans. by Edward Bellamy. Philadelphia: Lindsay and Blakiston.

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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding. (More? Embryology History \| Historic Embryology Papers)

PLATE XXVII

THE series of transverse sections from which the present and following plates were taken was made from the left arm of a man set. 40. The arteries were injected. The forearm was slightly flexed and pronated. In order to obtain bearing points for the individual laminae, a line was previously drawn passing through the middle of the biceps over the surface of the supinator longus to the thumb, and the uppermost points of each subsequent lamina lie in this line.

Fig. 1. In this instance the line of section passes through the middle of the arm, and its surface is seen from above downwards, hence we may imagine that we have the stump of an amputation of the right arm for examination, as has been before suggested in speaking of the lower extremity. The section is taken below the insertion of the deltoid, the biceps and triceps occupying the greater space. On the anterior aspect of the bone are portions of the brachialis anticus and coraco-brachialis ; in the middle, to the right of the observer, and between the flexor and extensor muscles, are the great vessels and nerves, and the musculo-spiral nerve has already commenced its tortuous course accompanied by the superior profunda artery. This position of the nerve accounts for the fact that blows or injuries from behind are capable of compressing it so directly upon the humerus that paralysis may be the result. The separation of the muscular masses of the flexors and extensors is already at this level so decided, that the intermuscular aponeurosis appears in the frontal plane. The relation of the individual muscles is so clear as hardly to demand any particular explanation.

Fig. 2 is a section of the left arm in the middle of its lower third. The flexor and extensor muscles lie on both sides of the humerus, and the intermuscular aponeuroses are here still more clearly seen than in the preceding section. In the external intermuscular septum is the musculo-spiral nerve, which has nearly terminated its half turn round the humerus, and behind it is the origin of the supinator longus. On the inner side the ulnar nerve has already become distinct from the great vessels and mass of nerves. The brachial artery is on the inner border of the biceps, accompanied by its venae comites, with the median nerve above it. Although its position is here very easily made out and its compression readily performed, there is great difficulty in isolating it and tying it unless the steps of the operation be carried out very correctly. The vessel, as the plate shows, cannot be directly cut down upon, as on account of nerves and veins which here often very freely anastomose, the operator may be much embarrassed ; and experience has shown that the vessel may be easily missed ; the surgeon must therefore make for the edge of the biceps, which is slightly in front of it, and open its sheath from the inner side, when he will come directly upon it.

The distance of the artery from the bone depends on the development of the brachialis anticus. In this instance, on account of the muscles in relation with it having become more developed, the vessel lies further from the bone than in the preceding section. Compare fig. 1 of this Plate, and also Plates X and XI, fig. 3.

Pig. 3. In this instance the plane of section passes through the lower end of the humerus and the olecranon. On the left side is the commencement of the capitellum with the end of the lateral epicondyle, on the left the trochlea with the middle epicondyle. The olecranon lies behind in the posterior supra-trochlear fossa. The extent of the cavity of the synovial membrane and capsule is indicated by a dark line.

Behind the olecranon is a large bursa between the skin and the tendon of the triceps. On the right, in the furrow between the olecranon and medial epicondyle is the ulnar nerve. To the left of the olecranon is the anconeus. The muscles of the arm are much reduced in bulk at their point of attachment. The origins, however, of the flexors and extensors of the hand and fingers, the pronator teres, and the supinator longus, the latter, on account of its high origin from the humerus, are more powerfully developed in the section. On the anterior aspect of the bones are masses of muscle, on the posterior merely ligaments and tendons, which allow of the bony prominences being clearly distinguished. This relation of the muscular masses, and the position of the vessel on the belly of the brachialis anticus, demonstrates the fact that all incisions which are intended to penetrate the joint should be arranged on its exterior aspect, as it can be here entered without fear of any considerable haemorrhage, and the ulnar nerve alone requires care in looking after.

Fig. 4 is a section of the forearm through the head of the radius, which is clearly shown with the annular ligament, and the upper extremity of the ulna the lesser sigmoid notch of which lies in articulation with the radius. The brachialis anticus is now for the most part tendinous, and attached to the ulna on the other side of its tuberosity. The tendon of the biceps is behind the tuberosity, which lies below the surface of the section, and the bursa, between it and the upper part of this tuberosity, is indicated by a black line. The brachial artery lies in the middle in front of the joint, enclosed by the origin of the flexors and extensors. Its division into radial and ulnar is evident. In front of it is the communication between the superficial and deep veins, and shows why bleeding in this region is so copious, if contraction of the muscles around the deep vein be induced ; it is, however, not possible to expose the intimate relations clearly by section. It may, however, be here explained that the "system" of the median vein does not only associate the trunks of the cephalic and basilic with each other, but also keeps up a communication with the deep veins accompanying the radial and ulnar arteries. The irregularly formed and generally small vein which lies in the bend of the elbow requires no particular note, as it possesses no further importance than the trunks which frequently approach close to the basilic and cephalic in the bend of the forearm. It is, however, worth while to designate this communication, which passes deep down, as median (it is named by Arnold, the deep median vein), and to denominate the oblique branches of communication between the basilic and cephalic as median basilic and median cephalic.

The mass of the flexor muscles is already at this level more strongly developed than in the preceding section. They predominate over the extensors, as will be still more clearly seen in the deeper section of the forearm.

FIG. 1. The section here passes through the upper third of the left forearm, and the ulna and radius exhibit surfaces of almost equal size, only the ulna with its sharp edge lies closer to the surface than the radius, which is embedded in muscle. The ulna can be readily felt throughout the entire length of the forearm, but the head and inferior extremity only of the radius. The edge of the ulna affords an easily distinguishable limit between the flexor and extensor muscles. The flexor carpi radialis forms the muscular limit on the flexor surface. It is placed with its tendinous border on the ulna, and covers over the deep flexor lying beneath it. On the opposite side of the ulna is the origin of the interosseous ligament, and in connection therewith fasciae, which pass directly upwards, and consequently separate both groups of muscles. To the left lie the supinators and extensors, and to the right the pronator teres and flexors. Between both groups of muscles are seen the vessels, the ulnar artery deep down, with the interosseous springing from it, and above it the radial. One needs merely to divide the enveloping fasciae, and to pull the muscle to one side to expose the , radial artery. The deep position of the ulnar at this spot renders its ligature difficult. Of nerves the superficial branch of the radial is found below the supinator longus, the deep branch lying in the supinator brevis. The median is between the pronator teres and flexor sublimis digitorum, the ulnar between the latter and flexor carpi ulnaris.

Peculiar interest is attached to the supinator brevis, the function of which can be readily understood by reference to this section. Passing outwards from the ulna (its upper set of fibres from the epicondyle are not seen), it wraps round the radius so that it must by its contraction roll it outwards. The space between it and the radius is taken up by the tendon of the biceps, which from the nature of its attachment assists in supination.

Fig. 2. In this plate, which, shows a section through the middle of the left forearm, there is considerably greater difficulty in recognising the relations of the individual structures than in the preceding, and this difficulty is not so much from the number of muscles, but from the absence of the fascial septa which limit the individual groups. The interosseous ligament alone forms with the skeleton an absolute limit, and this does not extend throughout the entire breadth of the section. The ulna and radius present their sharp edges to each other, and are bound together by the interosseous ligament ; on the right is the mass of the flexors, and on the left that of the extensors. Both groups of muscles are separated from the radius by a very thin fascial covering, which is attached to the radius and it encloses the radial artery and veins. This vessel is at this level easily found beneath the inner border of the supinator longus. The ulnar artery and nerves are here nearer the surface than in the preceding section, and the surgeon has only to make an incision between the flexor carpi ulnaris and the flexor sublimis digitorum to reach it. The fascial lamina passing from it to the median nerve, and which is prolonged beneath the origin of the pronator teres to the radius, divides the deep layer consisting of the flexor profundus digitorum and flexor longus pollicis from the superficial flexors, in which the flexor sublimis digitorum has penetrated beneath the palmaris longus which has already become tendinous. In like manner, on the opposite side of the interosseous ligament the extensors are divided into a superficial and deep layer ; and the extensor ossis metacarpi pollicis and the extensor secundi internodii are already shown.

If the flexor surface be compared with the extensor with reference to the mass of its muscles, it is seen at once that the flexor considerably predominates over the extensor, and farther that the main trunks of the vessels lie on the flexor surface. If the surgeon has a choice of flap in amputation of the forearm in this region, provided there is nothing to the contrary, he should form his flap chiefly from the flexor surface, as much on account of the quantity of soft parts as for the nourishment afforded the stump by the vessels. The formation of flaps from the extensor aspect is much more difficult of performance on account of the closeness of the bones to the surface.

Fig. 3 is a section of the left forearm in its lower third. The radius has become considerably thicker in section. Its surface is covered by the broad pronator quadratus, which from its attachment to the ulna, rolls the radius over to the position of pronation. Beneath it is the interosseous ligament, and on both sides of it the interosseous vessels. The proximity of the radio-carpal joint is evident from the presence of the tendons of the muscles. The flexors and extensors even to the flexor carpi ulnaris have become tendinous, consequently the radial artery lies free, covered only by skin and fascia, hence affording the readiest means of feeling the pulse, and is here very easily ligatured. The ulnar artery, on the contrary, is still covered over by the tendinous border of the flexor carpi ulnaris, which must be drawn aside in order to reach it. On the extensor aspect are the long muscles of the thumb, and passing upwards from below the radial extensors of the carpus. At their points of crossing, bursae are developed to prevent their rubbing against one another. Over-use of these muscles, such as with mowers, may cause inflammation of these bursae and form a tumour over this locality (tenosynovitis). The number of muscles again on the flexor surface exceeds that of the extensor surface in this section. The mass of the muscles has, however, so much diminished that in amputation of the forearm in this region the flap a la manchette is preferable, as the plate sufficiently explains.

Fig. 4. In this plate the section passes through the carpus. The tendons only of the muscles are now shown with their bursal tissue, the presence of which is indicated by the numerous black lines around the divided tendons, the only muscular tissue cut being that of the ball of the little finger. Only a small portion of the radius, the root of its styloid process, is shown.

The bones of the carpus seen, are the semilunar, scaphoid, and cuneiform, and the articulation between it and the pisiform, the surface of which is seen anteriorly, has been opened.

The three bones of the first row represent a surface, the individual portions of which are moveable, and which articulates with the radius, and with the ulna by means of the inter-articular fibro-cartilage. The section of these three bones, as here represented, has not the form of an ellipse, but resembles a parallelogram, with its angles rounded off. The articular surfaces of these bones approximate to the spherical form, being received into an oval hollow, somewhat in the same manner as the head of the humerus into the glenoid cavity of the scapula.

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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding. (More? Embryology History \| Historic Embryology Papers)

Reference

Braune W. An atlas of topographical anatomy after plane sections of frozen bodies. (1877) Trans. by Edward Bellamy. Philadelphia: Lindsay and Blakiston.

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Cite this page: Hill, M.A. (2024, May 3) Embryology Book - An Atlas of Topographical Anatomy 27. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_An_Atlas_of_Topographical_Anatomy_27

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