FRONT OF THE ARM 67 



distally as far as the elbow. Its filaments are distributed to 

 the skin over the lateral and anterior part of the distal half of 

 the arm. The larger lower branch can be followed as far as 

 the wrist, and not infrequently its terminal filaments even 

 reach the dorsum of the hand. It supplies the skin on the 

 dorsal aspect of the forearm. 



It should be borne in mind that the skin on the lateral 

 aspect of the limb, above these nerves and over the deltoid, 

 is supplied by the cutaneous branches of the axillary nerve 

 and the posterior supraclavicular nerves of the cervical plexus 



(P- 48). 



The lateral cutaneous nerve of the forearm is the terminal 

 part of the musculo- cutaneous nerve. It will be found 

 in front of the elbow-joint where it pierces the deep fascia on 

 the lateral side of the tendon of the biceps brachii. It is 

 a large nerve, and proceeds distally behind the median 

 cephalic vein. The skin, both upon the volar and dorsal 

 aspects of the lateral side of the forearm, is supplied by this 

 nerve, and it is distributed by two main branches. The 

 larger volar branch can be traced as far as the skin over 

 the ball of the thumb. A few of its terminal twigs pierce the 

 fascia above the wrist, and join the radial artery, by which 

 they are conducted to the dorsal aspect of the carpus. The 

 dorsal branch may be followed on the dorsal aspect of the 

 limb as far as the wrist. 



The intercosto-brachial nerve can usually be traced half-way 

 down the arm ; but the area of skin which it supplies 

 is somewhat variable. The posterior cutaneous nerve of the arm 

 is a branch of the radial (musculo-spiral) nerve. It proceeds 

 downwards and backwards on a deeper plane, and crosses 

 posterior to the intercosto-brachial nerve. Its filaments 

 extend upon the back of the arm as low as the elbow-joint. 



The medial brachial cutaneous nerve will be found piercing 

 the deep fascia, to become superficial, half-way down the medial 

 side of the arm. Its twigs may be followed, in the superficial 

 fascia, as' far as the olecranon. 



On the medial side of the arm, on its dorsal aspect, 

 three nerves therefore have been traced. From the medial 

 to the lateral side these are : the medial brachial cutaneous 

 nerve, the intercosto-brachial nerve, and the posterior cutaneous 

 brachial branch of the radial nerve (Fig. 28). 



The medial cutaneous nerve of the forearm (internal 



