1424 CLINICAL AND TOPOGRAPHICAL ANATOMY 



culo-spiral) and posterior branches of the musculo-cutaneous laterally, and the 

 posterior branches of the medial antibrachial cutaneous medially (fig. 1140). 



The lymphatics of the upper extremity are superficial and deep; the former 

 run with the superficial veins, the latter with the deep vessels. Occasionally a 

 few small nodes occur below the elbow. The epitrochlear nodes lie upon 

 the basilic vein, a little above the medial epicondyle and draining the fourth and 

 fifth digits. The majority of the lymphatics open into the axillary nodes, and 

 terminate, on the left side in the thoracic duct, on the right in the lymphatic duct. 

 A few, accompanying the cephalic vein, reach the subclavian or infraclavicular 

 nodes, and thus communicate with the lymphatics of the neck. 



It will be well briefly to consider here the chief results of paralysis of the main 

 nerves of the upper extremity. 



Paralysis of the median nerve. — (a) In forearm: Loss of pronation, (b) At lorist: Dimin- 

 ished flexion and tendency toward ulnar adduction, (c) In the hand: Power of grasp is lessened 

 especially in the thumb and lateral two fingers. Owing to the loss of flexion in the phalanges 

 of these fingers the phalanges are liable to become overextended by the action of the extensors 

 and interossei. The thumb remains extended, adducted, and closely appUed to the index, the 

 human characteristic being thus lost, and the ' ape's hand' of Duchenne being produced. Sensa- 

 tion will be lost over the palmar aspect of the thumb and lateral two and one-half fingers and 

 over the distal ends of the same fingers, to a varying degree, according to the sensory distribution 

 of the median and other cutaneous nerves. The above applies to lesions of the trunk. If the 

 nerve be injured at the ^\Tist, flexion of the wrist and fingers is less interfered with. 



Paralysis of the ulnar nerve. — (a) At urist: Power of flexion is diminished and that of ulnar 

 adduction lost, (b) In the hand: Power of grasp will be lessened in the ring and little fingers. 

 The interossei will be powerless to abduct or adduct the fingers, and there will be marked wasting 

 of the interosseous spaces and hypothenar eminence. The thumb cannot be adducted. After 

 a time, from paral3^sis of the lumbricals and interossei, the hand becomes 'clawed'— the first 

 phalanges overextended, and the second and third flexed (main en griff e). Sensation will be 

 lessened over the area suppHed by the nerve. 



Paralysis of the radial (musculo-spiral) nerve. — (a) In the forearm This is flexed, ex- 

 tension being impossible. The forearm is pronated, supination being impossible save by biceps, 

 which acts now most strongly on a flexed elbow-joint, (b) In the wrist: This is dropped, owing 

 to the loss of extension, (c) In the hand: The thumb is flexed and adducted. Some slight 

 power of extension of the second and third phalanges of the fingers remains by means of the 

 iumbricales and interossei. Sensation is impaired over the posterior and lateral aspect of the 

 forearm and lost to a varying extent over the distribution of the radial on the back of the hand. 



Paralysis of the deep radial (posterior interosseous) nerve. — The evidence here is somewhat 

 similar to that just given, but with the following differences, (a) In the forearm: There is no 

 loss of extension, and the loss of supination is less as the brachio-radialis is not paralysed, {b) 

 At the wrist: The 'drop' and loss of extension are not so marked, as the extensor carpi radialis 

 longus escapes. Sensation : There is no loss. 



Paralysis of the musculo-cutaneous nerve. — Forearm: Power of flexion is impaired, owing 

 to complete paralysis of the biceps and partial of the brachialis (anterior). Sensation: This is 

 impaired over the lateral aspect of the forearm, both back and front. 



Amputation of forearm. — The 'mixed' method by skin-flaps roundly arched and circular 

 division of the soft parts, the dorsal flap being the longer, is the most generally applicable. The 

 bones should always be sawn below the pronator teres, when possible. In sawing them they 

 must be kept parallel, the limb being in the supinated position. As the radius is the less securely 

 held above, it is well to complete the section of this bone first. The relative position of the ves- 

 sels has been indicated above (p. 1423, and figs. 1139 and 1141). 



THE WRIST AND HAND 



Bony points. — On the medial side the styloid process and, further laterally, the 

 head of the ulna can be made out. On the lateral side, the radial styloid process 

 descends about 1.2 cm. (^ in.) lower than that of the radius, and is somewhat ante- 

 rior to it. Abduction of the hand is thus less free than adduction. Between the 

 apex of the styloid process and the ball of the thumb a bony ridge can be felt, with 

 some difficulty, formed by the tubercle of the navicular and the ridge of the greater 

 viultangular (trapezium). At the base of the hypothenar eminence the pisiform 

 can lie more readily distinguished. The hook of the hainaiiim (unciform) lies below 

 and to the radial side of the pisiform. On the front of the metacarpo-phalangeal 

 joint of the thumb, the sesamoid bones can be distinguished. 



At the back of the wrist and hand the triquetrum (cuneiform) bone can be felt 

 V^elow the head of the ulna; and more toward the middle line the prominence of 

 the capitatum (os magnum), which supports the third or longest digit. 



A lino drawn from the base of the fifth metacarpal bone to the radio-carpal joint, slightly 

 curved downward, will give the line of the carpo-mctacarpal joints. (Windlc.) When the 

 fingers are flexed, it will be seen that in each case it is the proximal bone which forms the prom- 



