MUSCLES OF THE SHOULDER. 415 



The Supra-Spinatus Scapulce, 



Arises, fleshy, from the whole fossa supra-spinata, which it 

 fills up, and from its margins. Forwards it terminates in a 

 thick robust tendon closely connected with the capsular liga- 

 ment of the joint, and which passes under the jugum formed by 

 the articulation of the acromion with the clavicle. 



It is inserted, tendinous, into the inner face of the great tu- 

 berosity of the os humeri. 



It raises the arm, and turns it outwards. 



The Infra-Spinal us Scapulce, 



Arises, fleshy, from all that portion of the dorsum scapulae 

 below its spine, from the spine as far as the cervix, and from 

 the several margins of the fossa infra-spinata. Its fibres pass 

 obliquely to a middle tendon, which adheres closely to the 

 capsular ligament, and goes under the projection of the acro- 

 mion. 



This tendon is inserted into the middle facet of the greater 

 tuberosity of the os humeri. 



The infra-spinatus rolls the os humeri outwards and back- 

 wards. There is a bursa between its tendon and the scapula. 



The Tares Minor, 



Is situated at the inferior margin of the infra-spinatus, in the 

 fossa of the inferior costa scapulae, and looks very much like a 

 part of the infra-spinatus, to which it occasionally adheres so 

 closely as to be separated with difficulty. It arises, fleshy, from 

 the whole of the fossa, and the margins of the inferior costa, in 

 the space from the cervix of the bone to within an inch or so 

 of its angle. 



It is inserted, tendinous and fleshy, into the outer facet of 

 the great tuberosity of the os humeri, just below the infra-spi- 

 natus. 



It draws the os humeri downwards and backwards, and ro- 

 tates it outwards. 



