842 THE NERVOUS SYSTEM. 



crosses the annular ligament on the outer side of the pisiform bone, to the inner 

 side and a little behind the ulnar artery, and immediately beyond this bone divides 

 into two branches, superficial and deep palmar. 

 The branches of the ulnar nerve are 



^Articular (elbow). 

 Muscular. / q fi i i 



In the forearm < Cutaneous. In the hand < \ 



\ T\ i I Deep palmar. 



Dorsal cutaneous. 



^Articular (wrist). 



The articular branches distributed to the elbow-joint consist of several small 

 filaments. They arise from the nerve as it lies in the groove between the inner 

 condyle and olecranon. 



The muscular branches are two in number one supplying the Flexor carpi 

 ulnaris ; the other, the inner half of the Flexor profundus digitorum. They arise 

 from the trunk of the nerve near the elbow. 



The cutaneous branch arises from the ulnar nerve about the middle of the fore- 

 arm, and divides into two branches. 



One branch (frequently absent) pierces the deep fascia near the wrist, and is 

 distributed to the integument, communicating with a branch of the internal 

 cutaneous nerve. 



The second branch (palmar cutaneous) lies on the ulnar artery, which it 

 accompanies to the hand, some filaments entwining round the vessel ; it ends in 

 the integument of the palm, communicating with branches of the median nerve. 



The dorsal cutaneous branch arises about two inches above the wrist ; it passes 

 backward beneath the Flexor carpi ulnaris, perforates the deep fascia, and, along 

 the ulnar side of the back of the wrist and hand, divides into two digital branches, 

 of which one supplies the inner side of the little finger, and the other bifurcates 

 to supply the adjoining sides of the little and ring fingers ; it communicates with 

 the posterior branch of the internal cutaneous nerve, and sends a communicating 

 filament to that branch of the radial nerve which supplies the adjoining sides of 

 the middle and ring fingers. Sometimes there is a third digital branch which 

 goes to the adjacent sides of the middle and ring fingers. In this case the radial 

 nerve-supply is correspondingly diminished. 



The superficial palmar branch supplies the Palmaris brevis and the integu- 

 ment on the inner side of the hand, and terminates in two digital branches, which 

 are distributed, one to the ulnar side of the little finger, the other to the adjoining 

 sides of the little and ring fingers, the latter communicating with a branch from 

 the median. The digital branches are distributed to the fingers in the same 

 manner as the digital branches of the median. The dorsal digital branches, 

 except those on the little finger, do not extend, as a rule, beyond the second 

 phalanx, the remaining portion of the skin being supplied by filaments from the 

 corresponding palmar digital branch. 



The deep palmar branch passes between the Abductor and Flexor brevis 

 minimi digiti muscles, and follows the course of the deep palmar arch beneath the 

 flexor tendons. At its origin it supplies the muscles of the little finger. As it 

 crosses the deep part of the hand it sends two branches to each interosseous 

 space, one for the Dorsal and one for the Palmar interosseous muscle, the branches 

 to the Second and Third palmar interossei supplying filaments to the two inner 

 Lumbrical muscles. At its termination between the thumb and index finger it 

 supplies the Adductores transversus et obliquus pollicis and the inner head of the 

 Flexor brevis pollicis. Articular branches to the wrist are derived from this 

 nerve. 



The Musculo-spiral Nerve (Fig. 501), the largest branch of the brachial plexus, 

 supplies the muscles of the back part of the arm and forearm and the integument 

 of the same parts, as well as that of the back of the hand. It arises from the 

 posterior cord of the brachial plexus by a common trunk with the circumflex 



