138 



THE SKELETON. 



The clavicle is not uncommonly the seat of sarcomatous tumors, rendering the operation 

 of excision of the entire bone necessary. This is an operation of considerable difficulty and 

 danger. It is best performed by exposing the bone freely, disarticulating at the acromial end, 

 and turning it inward. The removal of the outer part is comparatively easy, but resection of 

 the inner part is fraught with difficulty, the main danger being the risk of wounding the great 

 veins which are in relation with its under surface. 



The Scapula. 



The Scapula (axo.7idvr], a spade) forms the back part of the shoulder girdle. It 

 is a large, flat bone, triangular in shape, situated at the posterior aspect and side of 



FIG. 94. Left scapula, anterior surface, or venter. 



the thorax, between the second and seventh, or sometimes the eighth, ribs, its 

 internal border or base being about an inch from, and nearly, but not quite 

 parallel with the spinous processes of the vertebrae, so that it is rather closer to 

 them above than below. It presents for examination two surfaces, three borders, 

 and three angles. 



The anterior surface, or venter (Fig. 94), presents a broad concavity, the sub- 



