266 Proceedings of the Royal Society of Victoria. 



and there may be a bi'anch of communciation between II. and 

 the coraco-clavicular after they have left III. Generally also, 

 a branch passes between III. and IV., most frequently running 

 from III. to IV. Sometimes also IV. is found fused with III. 

 at one point, or rarely, for some distance. Beyond its connection 

 with II. or IV., where such exists, the brachial nerve sends from 

 its posterior side a large branch to the Latissimus dorsi muscle, 

 with a twig to the Infraspinatus muscle. Then a nerve passes 

 off supplying the skin of the axilla and dorsal surface of the 

 upper arm. A short distance further a large branch runs off to 

 the pectoral muscles, while on its anterior face, the brachial 

 nerve sends off branches to the Delioideus muscle. Just beyond 

 the origin of these nerves, and as the brachial enters the arm, 

 or sometimes somewhat before, it divides, forming the radialis 

 and ulnaris nerves. 



The branches supplied by these two nerves are as follows : — 

 The ulnar nerve passes along the upper arm, merely giving off 

 one or two small branches to the skin of the inner surface. Just 

 above the elbow it gives off a large branch, the Cutaneus anti- 

 brachii inferior (dorsalis), which supplies chiefly the skin of the 

 dorsal surface of the hand. The Ulnaris continues its course into 

 the forearm and there gives off the Cutaneus antibrachii superior 

 nerve, passing to the skin of the inner side of the forearm. 

 Much lower down, the Ulnaris divides into two — the smaller 

 branch — Ulnaris medialis — supplies some of the flexor muscles 

 and digit V. : while the larger — Ulnaris lateralis — supplies 

 the adjacent sides of the digits II., III., IV., and V. : sending 

 also a branch to the flexor muscles of the palm. 



The radial nerve soon after its origin from the brachial gives 

 off twigs to the Delioideus and Subscapular muscles. Immedi- 

 ately below this is the Ramus cutaneus superior which supplies 

 the skin of the outer surface of the upper arm. Three twigs are 

 then given off" to the Triceps muscle, two of these being close 

 to the Ramus cutaneus superior, the other arising much lower. 

 "When it reaches the forearm the Radial nerve divides into the 

 Ramus radialis medialis — which supplies some of the extensor 

 muscles of the hand, the skin, and ends in digit V. — and the 

 Ramus radialis lateralis which supplies other of the extensor 

 muscles — and also by bifurcating branches, adjacent sides of the 

 digits II., III., IV. and V. 



