536 MAMMALIAN ANATOMY 



border of the body, is directed downward, forward, and inward, con- 

 tinuous with the upper border of the coracoid process. 



The outer surface of the head (Fig. 418) consists of three regions : 



(1) In front, occupying the anterior half, is a smooth, convex 

 triangle, which, facing outward and forward, turns inward and forward 

 to become the anterior surface of the coracoid process. It is pointed 

 below on the supraglenoid tubercle. The edge behind this part is the 

 margin of the glenoid cavity ; in front of the tubercle it runs upward 

 and forward ; it is sometimes flattened and sometimes notched, and 

 gives origin to the biceps and the coraco-humeral ligamenlj. It ends 

 by turning inward to become the lower border of the coracoid process. 



(2) Behind this triangular convexity on this surface of the head 

 is a narrow, flattened strip, lying below the spine. 



(3) Behind this strip is a wider portion which turns inward and 

 upward and is continuous with the infraspinous fossa. 



The inner surface of the head (Fig. 419) is alternately convex and 

 concave from before backward. From the lower, sinuous glenoid 

 border it slopes upward and outward. In front it curves inward and 

 backward on the posterior surface of the coracoid, and below the root 

 of this process it runs downward and forward on the supraglenoid 

 tubercle. At this point it often presents a decided circular fossa. 



The coracoid process 1 (Figs. 419, 422) springs from the inner 

 lower edge of the anterior border. It is wider at the base than at the 

 tip, and slightly less thick than wide. It is directed downward and 

 inward and curves backward. Its outer surface is therefore convex 

 in both directions and faces inward, forward, and upward. The poste- 

 rior surface is concave from above downward and from without 

 inward ; it therefore faces backward, outward, and downward. The 

 tip is evenly rounded, and gives attachment to the tendon of origin 

 of the coraco-brachialis muscle. 



Nomenclature. The word Scapula is used in the plural by 

 classical Latin authors to denote the back as contrasted with the breast. 

 In the Middle Ages spathula, the diminutive from the Greek spade, 

 and applied to a number of flat objects, was employed for the shoulder- 

 blade, but by the time of Vesalius it had been replaced by scapula. 

 Aristotle and Galen called the bone omoplate, from omos, the shoulder, 



1 From (Gr.) corax, a raven, and eides, like, because of a fancied resemblance 

 to a raven's beak. 



