THE SCAPULA. 



139 



scapular fossa. It is marked, in the inner two-thirds, by several oblique ridges, 

 which pass from behind outward and upward ; the outer third is smooth. The 

 oblique ridges give attachment to the tendinous intersections, and the surfaces 

 between them to the fleshy fibres, of the Subscapularis muscle. The anterior 

 third of the fossa, which is smooth, is covered by, but does not afford attach- 

 ment to, the fibres of this muscle. The venter is separated from the internal 

 border by a smooth, triangular margin at the superior and inferior angles, 

 and in the interval between these by a narrow edge which is often deficient. 



Groove for Dor^ 

 Scapulse Artery. 



FIG. 9"). Left scapula. Posterior surface, or dorsum. 



This marginal surface affords attachment throughout its entire extent to the 

 Serratus magnus muscle. The subscapular fossa presents a transverse depression 

 at its upper part, where the bone appears to be bent on itself, forming a consider- 

 able angle, called the subscapular angle, thus giving greater strength to the body 

 of the bone from its arched form, while the summit of the arch serves to support 

 the spine and acromion process. It is in this situation that the fossa is deepest, 

 so that the thickest part of the Subscapularis muscle lies in a line perpendicular 



