ULNAR. 573 



The digital branches are five in number. The first and second pass along the 

 borders of the thumb, the most external one communicating with branches of 

 the radial nerve. The third passes along the radial side of the index-finger, and 

 supplies the first Lumbrical muscle. The fourth subdivides to supply the adjacent 

 sides of the index and middle fingers, and sends a branch to the second Lumbrical 

 muscle. The fifth supplies the adjacent sides of the middle and ring fingers, and 

 communicates with a branch from the ulnar nerve. 



Each digital nerve, opposite the base of the first phalanx, gives off a dorsal 

 branch, which joins the dorsal digital nerve, and runs along the side of the 

 dorsum of the finger, ending in the integument over the last phalanx. At the 

 end of the finger, the digital nerve divides into a palmar and a dorsal branch ; 

 the former supplies the extremity of the finger, and the latter ramifies round and 

 beneath the nail. The digital nerves, as they run along the fingers, are placed 

 superficial to the digital arteries. 



The ULNAR NERVE is placed along the inner or ulnar side of the tipper limb, 

 and is distributed to the muscles and integument of the forearm and hand. It 

 is smaller than the median, behind which it is placed, diverging from it in its 

 course down the arm. It arises from the inner cord of the brachial plexus, in 

 common with the inner head of the median and the internal cutaneous nerves. 

 At its commencement, it lies at the inner side of the axillary artery, and holds 

 the same relation with the brachial artery to the middle of the arm. From this 

 point, it runs obliquely across the internal head of the Triceps, pierces the internal 

 intermuscular septum, and descends to the groove between the internal condyle 

 and olecranon, accompanied by the inferior profunda artery. At the elbow, it 

 rests upon the back of the 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 this muscle, covered by the integument and fascia. The 

 ulnar artery, in the upper part of its course, is separated from the ulnar nerve by 

 a considerable interval : but in the rest of its extent, the nerve lies to its inner 

 side. At the wrist, the ulnar nerve crosses the annular ligament on the outer side 

 of the pisiform bone, 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 : 



f Articular (elbow). 



Muscular. , Q - . , , 



In the forearm J Cutaneous. In hand I Superficial palmar. 



I Dorsal branch. 1 Deep palmar. 



[ 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 a superficial and deep branch. 



The superficial 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 deep branch lies on the ulnar artery, which it accompanies to the hand, 

 some filaments entwining round the vessel, which end 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 

 backwards beneath the Flexor carpi ulnaris, perforates the deep fascia, and, running 



