352 ABRAM T. KERR 



in 3 ; and from the first thoracic in 4. It must always be remem- 

 bered that the second thoracic is not considered in my records. 



Wichmann reports from the hterature 51 cases in which the 

 eighth cervical and first thoracic nerves entered the medial 

 antibrachial cutaneous and 38 in which the first thoracic only 

 enters the nerve. Schumacher found out of 10 cases that the 

 eighth cervical and first thoracic enter the nerve in 8 and the 

 first thoracic in 2. Adding the above to my records, w:e have the 

 possibility of the medial antibrachial cutaneous nerve deriving 

 its fibers from the eighth cervical and first thoracic in 226 cases; 

 the first thoracic alone in 44 cases and the seventh and eighth 

 cervical and first thoracic in 3. 



In 25 instances the medial antibrachial cutaneous nerve arises 

 from a common stem with the medial brachial cutaneous; in 

 9 with the medial anterior thoracic and in 9 with both of the 

 above nerves. In 10 instances it has a connection with the 

 intercostobrachial. In one of these the nerve is double and 

 both branches communicate. 



THE MEDIAL ANTERIOR THORACIC NERVE 



The medial (internal) anterior thoracic nerve is usually de- 

 scribed as arising from the caudal trunk of the brachial plexus. 



In my series there are 151 satisfactory records for this nerve. 

 In 105 of these, or 69.53 per cent, it arises from the medical 

 fasciculus of the plexus (fig. 3) ; in 38, or 24.50 per cent, it arises 

 from the caudal trunk of the plexus (fig. 2) ; in 3 from the eighth 

 cervical nerve (fig. 4) ; in one from the medial head of the median 

 nerve; and in one from the ulnar nerve; in 3 cases by two roots, 

 one from the medial fasciculus and one from the seventh cer- 

 vical nerve. 



Of the 105 cases that arise from the medial fasciculus of the 

 plexus, in 83 the nerve arises directly from the plexus, in one case 

 by two roots. In 9 of the 83 the nerve gives off a branch and 

 in one it receives a branch from the medial brachial cutaneous 

 nerve. In 4 instances the branch given off goes to the skin of the 

 arm, shoulder or axilla. In one it supplies an axillary slip of the 

 latissimus dorsi muscle. In this case the seventh cervical nerve 



