THE BRACHIAL PLEXUS. 773 



inner condyle, and passes into the forearm between the two heads of the Flexor 

 carpi ulnaris. In the forearm it descends in a perfectly straight course along its 

 ulnar side, lying upon the Flexor profundus digitorum, its upper half being covered 

 by the Flexor carpi ulnaris, its lower half lying on the outer side of the muscle, 

 covered by the integument and fascia. The ulnar artery, in the upper third of its 

 course, is separated from the ulnar nerve by a considerable interval, but in the 

 rest of its extent the ner.ve lies to its inner side. At the wrist the ulnar nerve 

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

 side of 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. /o fi . , , 



In the forearm < Cutaneous. In the hand < -^ 



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, running along the ulnar side of the back of the wrist and hand, divides into 

 branches ; one of these supplies the inner side of the little finger ; a second 

 supplies the adjacent sides of the little and ring fingers ; a third joins the branch 

 of the radial nerve which supplies the adjoining sides of the middle and ring 

 fingers, and assists in supplying them ; a fourth is distributed to the metacarpal 

 region of the hand, communicating with a branch of the radial nerve. 



On the little finger the dorsal digital branches extend only as far as the base 

 of the terminal phalanx, and on the ring finger as far as the base of the second 

 phalanx; the more distal parts of these digits are supplied by dorsal branches 

 derived from the palmar digital branches of the ulnar. 



The superficial palmar branch supplies the Palmaris brevis and the integument 

 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 deep palmar branch, accompanied by the deep branch of the ulnar artery, 

 passes between the Abductor and Flexor brevis minimi digiti muscles; it then 

 perforates the Opponens minimi digiti 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 



