410 MEDIAN NERVE BRANCHES. 



the internal and smallest of the branches of the axillary plexus ; it 

 arises from the plexus in common with the ulnar and internal head 

 of the median, and passes down the inner side of the arm in com- 

 pany with the basilic vein. At about the middle of the arm it pierces 

 the deep fascia by the side of the basilic vein and divides into two 

 branches, anterior and posterior. Each of these branches subdivides 

 into several filaments, which are distributed to the integument upon 

 the anterior and posterior aspect of the ulnar border of the fore-arm 

 as far as the wrist. At the bend of the elbow the filaments of the 

 anterior branch pass in front of the median basilic vein, and some- 

 times behind that vessel. On the fore-arm the nervous filaments 

 communicate with the external cutaneous and with the ulnar nerve. 



The LESSER INTERNAL CUTANEOUS NERVE or nerve of Wrisberg is 

 very irregular in point of origin. It is a long and slender nerve, and 

 usually arises from the common trunk of the last cervical and first 

 dorsal nerve. Passing downwards into the axillary space it com- 

 municates with the external branch of the first intercosto-humeral 

 nerve, and descends upon the inner side of the internal cutaneous 

 nerve, to the middle of the posterior aspect of the upper arm, where 

 it pierces the fascia and is distributed to the integument of the elbow, 

 communicating with the filaments of the internal cutaneous and 

 spiral cutaneous. In its course it gives off two or three cutaneous 

 filaments to the integument of the inner and anterior aspect of the 

 upper arm. 



The MEDIAN NERVE has received its name from taking a course 

 along the middle of the arm to the palm of the hand; it is, there- 

 fore, intermediate in position, between the radial and ulnar nerves. 

 It commences by two heads, which embrace the axillary artery ; 

 lies at first to the outer side of the brachial artery, which it crosses 

 at its middle ; and descends on its inner side to the bend of the elbow. 

 It then passes between the two heads of the pronator radii tercs and 

 flexor sublimis digitorum muscles, and runs down the fore-arm be- 

 tween the flexor sublimis and profundus, and beneath the annular 

 ligament into the palm of the hand. 



The branches of the median nerve are, 



Muscular, Superficial palmar, 



Anterior interosseous,. Digital. 



The Muscular branches are given oft' by the nerve at the bend of 

 the elbow ; they are distributed to all the muscles on the anterior 

 aspect of the fore-arm, with the exception of the flexor carpi ulnaris, 

 and to the periosteum. The branch to the pronator radii teres sends 

 off reflected branches to the elbow-joint. 



The interior interosseous is a large branch accompanying the 

 anterior interosseous artery, and supplying the deep layer of muscles 

 in the fore-arm. It passes beneath the pronator quadratus muscle, 

 and pierces the interosseous membrane near to the wrist. On 

 reaching the posterior aspect of the wrist it joins a large and 



