OSTEOLOGY. 63 



running on to tlie external surface of the bone, marking 

 the course of branclies of the iDOsterior scapular vessels. 

 The portion of the bone opposite this is more rounded than 

 the rest, and is termed the neck. Below it are the cora- 

 coid process anteriorly, the articulatory surface for the 

 humerus posteriorly. This articulatory surface occupies 

 the inferior angle. It is termed the glenoid cavity, and 

 is much smaller than the head of the humerus on which 

 it fits, thus allowing great range of action of the joint. It 

 looks slightly downwards and backwards, is shallow, and 

 presents a sharp margin, but at its antero-external part 

 manifests a slight tendency to extend on to the external 

 surface of the bone. At its anterior part it is divided mto 

 two by a groove into which, Avhen the limb is extremely 

 bent, coraco-humeralis tendon may fit. Externally to this 

 is a roughened prominence, near the articulatory surface. 

 The rest of the space between the coracoid process and 

 the glenoid cavity is smooth, and presents a large foramen 

 for a blood-vessel to pass into the bone. The sharp outer 

 circumferent margin of the glenoid cavity affords attach- 

 ment to the capsular ligament of the shoulder- joint. 



The external surface of the scapula is termed the 

 dorsum. It is convex in all directions, but ia hollowed out 

 in some parts in such a manner as to produce a very pro- 

 minent ridge, extending from the superior margin to the 

 neck, separating the anterior third from the posterior two 

 thirds of this surface. This is the spine, and separates 

 this surface into fossa antea sjnnatus anteriorly and fossa 

 ])ostea sinnatus posteriorly. At its attached margin, and 

 superiorly and inferiorly, this spine gradually blends with 

 the surface of the bone. Its free margin presents infe- 

 riorly a roughened prominence (corresponding to the acro- 

 mion i^rocess in man with which the clavicle articulates). 

 More superiorly the ridge presents a roughness which 

 culminates in an elongated prominence with a backward 

 curve, the tubercle, to which the inferior anglo^ of tra- 

 pezius is attached. The spine anteriorly affords attachment 

 to antea spinatus, posteriorly to postea spinatus ; also 

 levator humeri, teres externus, and (indirectly) pectoralis 

 anticus gain attachment to its edge. Fossa antea spinatus 

 is bounded anteriorly by the anterior margin, posteriorly, 

 for the most part, by the spine, superiorly by the postero- 

 superior margin, inferiorly it becomes widened in forming 



