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point draw a line obliquely distally and forwards to the front of the lateral epicondyle, where the nerve divides into its superficial and deep branches. To map out the nerve as it lies in the radial groove, draw a line from the same point obliquely proximally across the prominence formed by the lateral head of the triceps to the junction of the posterior fold of the axilla with the arm. In fractures of the humerus in the neighbourhood of the insertion of the deltoid, the nerve is not infrequently lacerated, or so involved in the callus as to produce the condition known as "drop-wrist," the result of paralysis of the extensor muscles of the forearm. To cut down upon the nerve, commence the incision a little distal to the point where it pierces the lateral intermuscular septum, and carry it obliquely proximally and slightly backwards through the lateral head of the triceps.
The shaft of the humerus, nowhere subcutaneous, is most readily manipulated in the region of the insertion of the deltoid, proximally along the lateral head of the triceps, and distally behind the lateral supracondylar ridge. The surgical neck, situated between the tubercles and the attachments of the muscles inserted into the region of the intertubercular sulcus, is related to the lateral wall of the axilla, and is on a level with the junction of the proximal and middle thirds of the deltoid; at the same level are the circumflex vessels and the axillary nerve.
The shaft may be cut down upon with least injury to soft parts: (1) in its proximal third, anteriorly, by an incision extending distally through the anterior fibres of the deltoid, parallel, and a little lateral, to the intertubercular sulcus; the sheath of the biceps will thus be avoided, and the small, anterior circumflex artery will be the only vessel divided. (2) In the proximal third, posteriorly, by an incision through the posterior fibres of the deltoid, the bone being reached just lateral to the origin of the lateral head of the triceps, thus avoiding the radial nerve; the circumflex vessels and the axillary nerve will be exposed at the proximal part of the wound. (3) In the distal third, by an incision extending upwards from the back of the lateral epicondyle a little to the medial side of the lateral intermuscular septum.
In injuries about the elbow the diagnosis rests mainly upon the relative positions of the bony points, which are, therefore, of great importance. The epicondyles of the humerus are both subcutaneous and upon the same level, the medial being the more prominent. In the extended position of the elbow the tip of the olecranon is on a level with a line joining the epicondyles; when the forearm is flexed the olecranon descends, and when full flexion is reached it lies 1 in. distal to the epicondyles, and in a plane anterior to the posterior surface of the distal end of the humerus. The head of the radius, which lies nearly 1 in. below the lateral epicondyle, is best manipulated from behind by placing the thumb upon it, while the semi-flexed forearm is being alternately pronated and supinated. Upon the lateral part of the posterior aspect of the extended elbow is a distinct dimple, which overlies the radio-humeral articulation; this dimple, along with the hollows on each side of the olecranon, becomes effaced in synovial thickenings and effusions into the joint. The coronoid process is situated too deeply to be distinctly felt. The distal epiphysis of the humerus includes the articular portion of the distal extremity and the lateral epicondyle; it is, therefore, small and almost entirely intra-articular, so that foci of disease in its neighbourhood soon invade the cavity of the joint. The medial epicondyle ossifies as a separate epiphysis which unites with the distal end of the diaphysis. In interpreting skiagrams of the elbow of children about six years of age and upwards, care must be taken not to mistake the centre of ossification in the lateral portion of the distal epiphysis of the humerus for a fracture. In the commonest dislocation of the elbow, viz., with backward displacement of both bones of the forearm, the normal relative position of the bony points is lost, whereas in a transverse supracondylar fracture the normal relations are maintained. In the child the head of the radius is relatively smaller, and less firmly kept in position by the annular ligament than in the adult, so that it is liable to be partially dislocated, giving rise to the condition known as "pulled elbow."
To evacuate pus from the elbow-joint a vertical incision should be made over the dorsal aspect of the joint, imtmediately lateral to the olecranon.
The median vein is seen to bifurcate into the median basilic and median cephalic veinsin. distal to the middle of the bend of the elbow; opposite the same point, but beneath the deep fascia, is the bifurcation of the brachial artery. The median basilic and median cephalic veins diverge as they ascend one on each side of the biceps tendon; the larger of the two veins, viz., the median basilic, is usually selected for the operations of venesection and transfusion. When the elbow flexed the biceps tendon can be traced vertically through the centre of the bend of the elbow almost to its insertion. Passing distally and medially from the medial
Vena comes of brachial artery
Lateral cutaneous nerve of forearm
Median cephalic vein
Median basilic vein
Vena comes of brachial artery
Articular surface of humerus
Olecranon fossa of humerus
edge of the tendon is the lacertus fibrosus, which separates the median basilic vein from the brachial artery. If the finger nail is insinuated beneath the medial edge of the lacertus fibrosus the point of the finger will rest upon, and feel the pulsations of, the brachial artery. The median nerve descends through the space a little medial to the brachial artery. The bifurcation of the radial nerve takes place in front of the lateral epicondyle under cover of the brachio-radialis. The ulnar nerve can be rolled beneath the finger upon the back of the medial epicondyle; its position renders it liable to injury in severe fractures about the elbow; and in excising the joint care must be taken not to injure the nerve.
THE FOREARM AND HAND.
The proximal half of the radius is deeply placed; the distal half, however, is easily palpated. The anterior border of its distal extremity is felt as a prominent transverse ridge, situated 1 in. proximal to the thenar eminence; immediately distal to the ridge is the radio-carpal articulation. The tip of the styloid process, situated nearly in. more distal than that of the ulna, is deeply placed at the lateral side of the wrist, in the hollow between the extensor tendons of the first and second phalanges of the thumb. Upon the middle of the posterior surface of the distal end of the radius is the dorsal radial tubercle, which intervenes between the extensor pollicis longus and the short radial extensor of the wrist. the tubercle can be distinctly felt, and may be taken as a guide to the proximal end
of Lister's dorso-radial incision for excision of the wrist. The dorsal border of the ulna is subcutaneous throughout, and may be felt along the interval between the flexor and extensor carpi ulnaris muscles. Upon the ulnar side of the dorsal aspect of the wrist, when the forearm is in the prone position, there is a well-marked rounded prominence formed by the distal extremity of the ulna, anterior to which is the styloid process, the deep groove between the two being occupied by the tendon of the extensor carpi ulnaris.
Median cephalic vein
The carpal bones are built up so as to form an arch, converted by the transverse carpal ligament into a tunnel for the transmission of the flexor tendons. At each extremity of the arch the two bony points to which the ligament is attached furnish important landmarks. These bony points are: laterally, the tuberosity of the navicular and the ridge of the greater multangular bone; medially, the pisiform and the hamulus of the os hamatum. The tuberosity of the navicular is felt immediately proximal to the root of the thenar eminence, midway between the tendons of the abductor pollicis longus and the flexor carpi radialis; in. distal to the tuberosity of the navicular is the ridge of the greater multangular bone, felt deeply beneath the medial part of the thenar eminence. At the root of the hypothenar eminence, and crossed by the crease which separates the forearm from the hand, is the pisiform bone, proximal to which is the tendon of the flexor carpi ulnaris, passing to be inserted into it. The hamulus of the os hamatum is felt deeply beneath the radial side of the hypothenar eminence, and a full finger's breadth distal and lateral to the pisiform.
The bases of the first, third, Band fifth metacarpals, all of which
Deep ramus of
Radial nerve (superficial ramus)
Tendon of flexor carpi
Deep volar arch
Transverse carpal ligament
FIG. 1115.-BEND OF ELBOW, VOLAR SURFACE OF FOREARM,
can be readily identified on the dorsal aspect, furnish a sufficient guide to the line of the carpo-metacarpal articulations. At the base of the third metacarpal is a tubercle, which can be felt projecting from its dorsal aspect at a point 1 in. vertically distal to the tubercle upon the back of the distal end of the radius. This metacarpal tubercle marks the insertion of the extensor carpi radialis brevis, the favourite site for the development of a "ganglion," which may frequently be ruptured by pressing it firmly against the tubercle. Anteriorly, the carpo-metacarpal articulations correspond to the distal border of the transverse carpal ligament.
The prominences of the knuckles are formed entirely by the heads of the metacarpal bones. Anteriorly, the metacarpo-phalangeal articulations are situated
in. proximal to the level of the web of the fingers; posteriorly, the joints may be ateral felt as a groove immediately proximal to the projecting ridge at the base of the first the phalanges. A well-marked crease crosses obliquely over the anterior aspect of the the s metacarpo-phalangeal joint of the thumb. To cut into the first interphalangeal joints t from the front, incise along the most proximal of the creases in front of the joints; st whereas to cut into the terminal joints, incise along the most distal of the creases in Ta
front of the joints. Dorsally, the first and the terminal interphalangeal articulations are opposite the most distal of the various creases overlying the joints. The most important muscular landmarks upon the front of the forearm are the brachio-radialis, the flexor carpi radialis, and the pronator teres. radialis is thrown into prominence by flexing the semi-prone forearm against resistance. At the junction of the proximal and middle thirds of the forearm the pronator teres passes under cover of the brachio-radialis; between the two is the radial artery. The tendon of the flexor carpi radialis forms a prominent landmark descending along the middle of the volar aspect of the forearm towards the ridge of the multangulum majus; the tendon of the palmaris longus, when present, is seen to its medial side.
At the dorsum of the forearm the intermuscular septum between the radial and common extensors corresponds to the proximal part of a line extending from the lateral epicondyle of the humerus to the tubercle on the dorsum of the distal end of the radius. The dorsal interosseous nerve, at the point at which it emerges from the substance of the supinator muscle, will be found at the bottom of this septum, 2 in. distal to the head of the radius; below that point the septum is the best line along which to cut down upon the posterior surface of the radius. Winding across the distal third of the dorsal surface is an oblique prominence, caused by the abductor pollicis longus and extensor pollicis brevis muscles.
The flexor sheaths of the palm and of the digits are of surgical importance in consequence of their liability to suppurative inflammation. The common flexor sheath begins 1 in. proximal to the transverse carpal ligament, under which it extends to a little beyond the middle of the palm. The digital flexor sheaths extend from the bases of the terminal phalanges to the level of the distal transverse crease of the palm, opposite the necks of the metacarpal bones, with the exception of the sheath of the little finger, which is continuous with the common flexor sheath of the palm. The sheath of the flexor pollicis longus extends from the base of the terminal phalanx proximally to a point about 1 in. proximal to the transverse carpal ligament; it frequently communicates with the common flexor sheath. From this anatomical arrangement it follows that suppuration in the sheaths of the little finger and