PLATE XII. 



THE BACK OF SHOULDER. 



This plate shows a superficial dissection of the 

 muscles at the back of the shoulder, and also the 

 nerves and vessels of the arm from behind, the 

 arm having been strongly rotated inwards. 



The cutaneous nerves which supply this region 

 are : (a) Acromial branches of the third and fourth 

 cervical nerves ; (b) cutaneous branches of the poste- 

 rior primary divisions of the spinal nerves ; (c) poste- 

 rior twigs of the lateral branches of the intercostals ; 

 (d) circumflex ; (e) internal cutaneous branch of mus- 

 culo-spiral ; (/) intercosto-humeraL 



The internal cutaneous branch of the musculo-spiral, as shown in the plate, was 

 smaller than usual, and only supplied the skin about half-way down the back of the 

 arm instead of nearly reaching the olecranon, as generally described. The branches of 

 the intercosto -humeral, on the other hand, were large, and supplied the skin nearly 

 down to the olecranon. The usual branch of communication between the intercosto- 

 humeral and internal cutaneous of the musculo-spiral could not be found. 



There is generally a fibrous band uniting the tendon of the latissimus dorsi and the 

 scapular head of origin of the triceps, which is the remains of a muscle the dorsi- 

 epitrochlearis. 



