THE SHOULDERS. 185 



The posterior or vertebral margin of the scapula is the long- 

 est of the three, and is called the base. It is not perfectly 

 straight, but somewhat rounded, especially above the spinous 

 process; and has there varied degrees of obliquity in different 

 persons. This margin, below the spine, receives the rhomboi- 

 deus major muscle, and above the spine, the levator scapulae; 

 at the part between the other two, the rhomboideus minor is 

 inserted. 



The external or axillary margin of the scapula, also called 

 the inferior costa, is much the thickest of the three. A superfi- 

 cial fossa placed somewhat posteriorly, forming the inferior 

 boundary of the fossa infra-spinata, begins about two inches 

 from its inferior extremity, and running up to the neck of the 

 bone, lodges the teres minor muscle. On the exterior face of 

 the inferior angle is a flat surface, from which the teres major 

 muscle and a slip of the latissimus dorsi arise. At the fore 

 part of this surface the inferior costa is elongated into a kind 

 of process. Just below the glenoid cavity is a small ridge for 

 the origin of the long hea,d of the triceps muscle. 



The superior margin or costa of the scapula, is the shortest 

 and thinnest of the three, and is terminated in front by the co- 

 racoid notch between it and the coracoid process. The notch 

 is converted into a hole by a ligament, in the living state, and 

 through it pass the upper scapular nerve and blood vessels. 



The glenoid cavity for articulating with the os humeri, sup- 

 plies the place of the anterior angle of the scapula. It is very 

 superficial, and ovoidal, with the small end upwards. Just at 

 the upper end is a small flat surface, from which the long head 

 of the biceps arises. The glenoid cavity is fixed on the cervix, 

 as it is called, at which a general increase in the thickness of the 

 bone occurs, in order to give a strong foundation to this cavity. 

 From the superior part of the cervix arises the coracoid pro- 

 cess, the base of it being bounded in front by the glenoid cavi- 

 ty, and behind by the coracoid notch. The base rises upwards 

 and inwards for half an inch, and what remains of the process, 

 then, runs horizontally inwards and forwards, to become small- 

 er, and terminate in a point. This point is advanced beyond 



16* 



