THE SCAPULA 79 



(scapular tuberosity), and passing out and forward from it 

 the trapezoid line. 



The sternal end is thick and projects in an angle downward 

 and backward, its triangular concavoconvex surface looking 

 a little downward and forward. The scapular end is so bevelled 

 as to rest upon the acromion, the small articular surface look- 

 ing down and out; this end is normally a little higher than 

 the acromion on which it rests. 



The scapula is a large triangular flat bone, situated at the 

 posterior and lateral aspect of the chest, between the second 

 and seventh ribs of the seventh interspace. Its posterior border 

 is about 1 inch from and parallel with the vertebral spines. 

 It is attached to the trunk by the clavicle and by muscles, 

 and from it is suspended the humerus. 



The bone consists of a large triangular blade or body, and 

 two processes, the coracoid and spine, and presents for exami- 

 nation two surfaces, three borders, and three angles. The 

 anterior surface, or venter, looks forward, downward, and inward, 

 and presents the subscapular fossa, marked by three or four 

 converging oblique lines, giving attachment to tendinous 

 intersections of the subscapular muscle. The deepest part 

 of the fossa is the subscapular angle, where the bone seems 

 bent on itself, so that the thickest part of the muscle is per- 

 pendicular to the plane of the glenoid cavity, and can act 

 most advantageously. Separated from this fossa are two 

 flat surfaces, one at the upper angle and one at the lower; 

 with the line connecting them close to the vertebral border 

 they give attachment to the serratus magnus muscle. 



The posterior surface, or dorsum, is divided by the spine 

 into two unequal fossae, the supraspinous and infraspinous. 

 The supraspinous is less than half the size of the infraspinous 

 fossa. It is smooth, concave, and broader at its vertebral 

 than at its humeral end, and gives origin by its inner two- 

 thirds to the supraspinatus muscle. 



The lower fossa is marked near the centre by a convexity 

 corresponding to the concavity of the venter; on either side 

 of this is a groove, the external one being deep and bounded 

 by the axillary border. Near the inner border are short lines 



