184 SKELETON. 



obliquely towards the anterior angle, ceases somewhat short of 

 it; it is then elongated forwards and upwards, so as to overhang 

 the shoulder joint, and to form the acromion process. The ca- 

 vity above the spine is owing principally to the elevation of 

 the latter, and is called the fossa supra-spinata; it is occupied 

 by the supra-spinatus muscle. The cavity below the spine is 

 the fossa infra-spinata, and is for the infra-spinatus muscle: it is 

 bounded below by a rising of the external margin of the bone. 

 The middle of this fossa presents a swell or convexity, which 

 is a portion of the general convexity presented by the posterior 

 face of the bone. The spine of the scapula is always promi- 

 nent in the outline of the shoulder, and has a well secured base 

 along the whole of its attachment to the bone, to where it ter- 

 minates in the acromion process. It leans upwards, and from 

 the increased breadth of its summit, is concave both above and 

 below. The summit itself is somewhat rough, and has inserted 

 into its superior margin the trapezius muscle, while the infe- 

 rior margin gives origin to the deltoid. The little triangular 

 face at the commencement of the spine is made by the tendon 

 of the trapezius muscle gliding over it. The acromion process 

 arises from the spine by a narrow neck, is triangular, nearly 

 horizontal, and overhangs the glenoid cavity, being elevated 

 about one inch above it. It is slightly convex above and con- 

 cave below: the external and the internal margins are the long- 

 est. The posterior margin is continuous with the inferior edge 

 of the spine of the scapula; and the internal is on a level with 

 the clavicle. At the fore extremity of the internal margin, is a 

 small, oval, articular face, by which the acromion unites with 

 the clavicle. The margins of the' acromion, with the excep- 

 tion of the internal, are rough, and give origin to the deltoid 

 muscle. 



The anterior or costal face of the scapula is concave, and 

 obtains the name of the sub-scapular fossa or venter. It is oc- 

 cupied by the sub-scapular muscle; the divisions of which, by 

 leaving deep interstices between them, produce corresponding 

 ridges upon the bone, that run obliquely upwards and outwards. 

 Along the whole posterior margin of this face of the scapula, 

 is inserted the serralus major anticus. 



