UPPER EXTREMITY. 



BONES. 



Clavicle. This has a shaft and two extremities, inner 

 (sternal) and outer (acromial). The sternal end is enlarged 

 and presents a facet, for the manubrium, which is convex 

 antero-posteriorly and slightly concave vertically; the edge 

 around the facet is rounded below but sharp elsewhere. The 

 shaft is curved with the convexity in front in its inner two- 

 thirds, and behind in its outer third. The anterior border is 

 rough internally ; externally it is sharper and often has a spur 

 (deltoid tubercle). The posterior border is broad internally 

 but more rounded externally, where a marked projection 

 (conoid tubercle) marks its union with the acromial end. The 

 superior surface is smooth and looks upward and forward. 

 The inferior surface looks downward and backward; near its 

 sternal end is an impression for the rhomboid ligament; ex- 

 ternal to this is a groove, for the Subclavius, running almost 

 to the conoid tubercle. The acromial end is flattened vertically 

 and expanded transversely. The anterior edge is sharp, the 

 posterior is rougher, and the outer edge has an oval facet for 

 the acromion process. The upper surface is smooth. The 

 under surface has a ridge (trapezoid, or oblique) running 

 obliquely from behind forward and outward to join the pos- 

 terior border at the conoid tubercle. [184] 



Scapula. This is triangular and flattened; it has two sur- 

 faces, dorsal and ventral. The body has three borders and 

 three angles. The superior border, the shortest, runs from the 

 superior angle almost to the root of the coracoid process and 

 there presents a notch (suprascapular) . The internal (verte- 



[141] 



