22 Anatomy Applied to Medicine and Surgery. 



The Structures Surrounding the Joint, from 

 without, inwards, are: The skin, supplied by the supra- 

 acromial and circumflex nerves ; next, the superficial and 

 deep fasciae, the latter blending with the fascia covering 

 the infra-spinatus and the pectoralis major; then the del- 

 toid, while, beneath this muscle and between it and the 

 capsule of the joint, is a thin though strong layer of 

 areolar tissue. To facilitate the movements of the del- 

 toid over the head of the huimerus, a synovial bursa 

 is found in the substance of this areolar tis- 

 sue, and is situated, therefore, between the capsule 

 of the joint and the under surface of the deltoid mus- 

 cle. This, termed the sub-acromial bursa, is somewhat 

 lozenge-shaped, one extremity extending down the outer 

 surface of the joint to about the level of the lower facet of 

 the greater tuberosity; the other, upwards and inwards, 

 beneath the inferior surface of the acromion, to a point 

 about one inch from the free margin of that process. The 

 muscles intimately connected with the joint are: Above, 

 the supra-spinatus ; behind, the infra-spinatus and the 

 teres minor ; in front, the subscapularis ; below, the triceps 

 and, within the joint, the biceps. These, with the excep- 

 tion of the biceps, are all attached to the capsular ligament 

 by their under surfaces, and act as elastic ligaments for 

 the joint, while, at the same time, they prevent the capsule 

 and synovial membrane from being "tucked" in between 

 the bones in the different movements of the joint. 



The other muscles not directly connected with the 

 articulation but of importance because of their action on 

 it, are: The deltoid, the coraco-brachialis, latis'simus 

 dorsi, teres major, and the pectoralis major. 



Actions of the Muscles controlling the shoulder 

 joint : 1. The supra-spinatus, arising from the internal 

 two-thirds of the supra-spinous fossa, and inserted into 



