L02 ANATOMY IN A NUTSHELL. 



The ulnar nerve arises a little below the lower border of the Pectoralis 



minor, from the inner cord of the brachial plexus. Its fibers may be traced to 

 the eighth cervical and firsl dorsal. It lies on the inner side of the axillary 

 artery, also of brachial artery, until it passes below the insertion of the Coraco- 

 brachialis where it forms an acute angle, and, in company with the posterior 

 branch of the inferior profunda artery, pierces the internal intermuscular septum, 

 then passing down to the groove between the internal condyle and the ole- 

 cranon process it gives off two or three branches to the elbow-joint, then passes 

 between the two heads of the Flexor carpi ulnaris in company with the pos- 

 terior ulnar recurrent artery. In the forearm it lies between the Flexor pro- 

 fundus digitorum ami Flexor carpi ulnaris; in the middle third of the forearm 

 between the same two muscles with the Flexor sublimis digitorum on the other 

 side. It is situated on the inner side of the ulnar artery and crosses the anterior 

 annular ligament on the radial side of the pisiform. In the forearm it gives off 

 branches near the elbow-joint which supply the Flexor carpi ulnaris and the 

 inner part of the Flexor profundus digitorum. 



The cutaneous branches arise about the middle of the forearm; there are 

 two of these branches. The one most superficial pierces the deep fascia near 

 the wrist to supply the integument and anastomose with the internal cutane- 

 ous. The other branch, which is the deeper one, is called the palmar cutane- 

 ous. It accompanies the ulnar artery, being upon its anterior surface, to the 

 hand. 1 he dorsal cutaneous arises about two or three inches from the wrist; 

 it passes to the dorsal aspect of the wrist under the Flexor carpi ulnaris, super- 

 ficial to the Extensor carpi ulnaris to supply the integument on the ulnar as- 

 pect of the dorsum of the hand and that of the little and half of the ring fingers. 



The superficial terminal or palmar branch supplies the Palmaris brevis, 

 the hypothenar eminence, the inner side of the little finger on its volar aspect, 

 and the contiguous sides of the little and ring fingers. The deep palmar arch 

 or branch passes between the Abductor minimi digiti and Flexor brevis minimi 

 digiti. then through the Opponens minimi digiti to the deep surf ace of the flexor 

 tendons and their synovial sheaths. It supplies the Abductor minimi digiti, 

 Flexor brevis minimi digiti. opponens minimi digiti, two inner Lumbricales, 

 all the [nterossei, Adductor transversus pollicis, Adductor obliqus pollicis, and 

 inner head of the Flexor brevis pollicis and occasionally the outer head. 



The ulnar nerve SUppileS eighteen muscles. 



The musculO-CUtaneOUS or external cutaneous (perforans Casserii) comes 

 from the outer cord and its fibers may be traced to the fifth, sixth, and seventh 

 cervical nerves. It supplies muscles in the arm but no integument, whereas it 

 supplies integument in the forearm but no muscles. It begins opposite the 

 lower border of the I Vctoralis minor, passing outward and downward to pirece 

 the Coraco-brachialis which it supplies. It divides in the substance of this 

 muscle and passes to the outer side of the arm between the Biceps and the 

 Brachialis amicus, supplying these muscles. It sends a branch with the nutri- 

 ent artery into the bone. The branch to the Coraco-brachialis is given off 

 from the nerve close to its origin. Occasionally this muscle is supplied by a 

 separate branch from the outer cord. The branch to the Brachialis amicus 



