ULNAR NERVE 817 
ULNAR NERVE 
The ulnar nerve (Figs. 566, 567, 568, 652) arises with the median from the 
thoracic components of the brachial plexus. It descends between the brachial 
artery and vein, accompanied for a short distance by the radial nerve. It then 
crosses the vein and continues behind the latter along the anterior border of the 
tensor fasciz antibrachii and dips under that muscle near the elbow. Here it is 
joined by the ulnar vessels and passes downward and backward over the medial 
epicondyle of the humerus. In the forearm it crosses obliquely the deep face of the 
ulnar head of the flexor carpi ulnaris and descends under the deep fascia with the 
Extensor carpi radialis 
Intermuscular septwm 
Common extensor of digit 
Accessory cephalic vein 
Vein 
Cephalic vein 
Medial ligament of elbow 
Intermuscular septum ZZ *\ OM MM edian nerve 
Lateral extensor of digit <r x Median veins 
Intermuscular septum . : w Median artery 
Uinariatlateralis Flexor carpi radialis 
Deep digital flexor 
(humeral head) 
Superficial digital flexor SS Owe Bet Vf _ Flexor carpi ulnaris 
Deep digital flexor (ulnar head) 
Ulnar vein 
Ulnar artery 
Ulnar nerve 
Fic. 653.—Cross-sEcTION OF Forearm OF Horse aBout THREE INCHEs (CA. 8 CM.) BELOW THE ELpow Jornt. 
The deep fascia is designated by red line. N, A, V, Dorsal interosseous vessels and nerve. 
vessels, at first on the ulnar head of the deep flexor, and then between the middle 
and lateral flexors of the carpus. Near the level of the accessory carpal bone it 
divides into two terminal branches, superficial and deep. It gives off two principal 
collateral branches. The cutaneous branch (Ramus cutaneus volaris) is detached 
just before the nerve passes under the tensor fascize antibrachii; it runs downward 
and backward on that muscle under cover of the posterior superficial pectoral, 
becomes superficial below the elbow, and ramifies on the posterior surface and both 
sides of the forearm. The muscular branches, which are given off at the elbow, 
supply the superficial digital flexor, the ulnar head of the deep flexor, and the flexor 
carpi ulnaris. Of the two terminals, the superficial branch (Ramus superficialis) 
emerges between the tendons of insertion of the lateral and middle flexors of the 
carpus and ramifies on the dorso-lateral aspect of the carpus and metacarpus. The 
deep branch (Ramus profundus), after a very short course, unites under cover of 
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