250 



HUMAN ANATOMY. 



the vertebral border. These surfaces are separated from the rest of the fossa by 

 well-marked lines, which, with some four ridges running forward and upward from the 

 spinal border, giv^e origin to tendinous septa from which the subscapularis springs. 

 This muscle arises also from the deep groove inside the axillary border. 



The posterior surface,' or dorsum, is divided by the spine into a supraspinous 

 and an infraspinous fossa. The former gives origin to the supraspinatus. Near the 

 back it is often strengthened by a vertical swelling. The infraspinous fossa is chiefly 

 occupied by the infraspinatus, but two other areas are marked off by two lines : one, 

 running forward and upward, separates the dorsal side of the lower angle and of the 

 unnamed process on the axillary border ; from this space springs the teres major. 

 The second line leaves the axillary border near the glenoid cavity and, diverging 

 slightly, strikes the former line near the front, bounding a narrow region for the 

 teres minor, which is crossed high up by a groove for the dorsal scapular artery. 



Fig. 269. 



Anterior tubercle acromion 

 Coraco-acromial ligament^ 



Short head of biceps 



CORACOID PROCESS 



Long head of biceps 



Suprascapular notch 



Upper part of vertebral border 



Metacromial tubercle 



SUPERIOR ANGLE 



Right scapula from above. 



The spine ^ is a triangular plate arising from a small triangular surface at the pos- 

 terior border, running outward and somewhat upward. Its attached border stops at 

 the neck before reaching the glenoid cavity. The spine forms an acute angle with 

 the floor of the supraspinous fossa, and an obtuse one with that of the infraspinous. 

 Its front border is rounded and curves forward, and forms the posterior boundary 

 of the great scapular notch connecting the supra- and infraspinous fossae. The free 

 border is narrow beyond the triangular area, but soon broadens, presenting an upper 

 and a lower lip. The descending fibres of the trapezius are inserted into the whole 

 length of the former, and of its continuation into the acromion. The lower lip often 

 begins with a tubercle for the ascending and horizontal fibres, a little beyond which 

 it narrows again. It gives origin to the deltoid muscle, which also is continued 

 along the acromion. 



The acromion^ is a broad, flat expansion overhanging the shoulder-joint and 

 articulating with the clavicle by an elongated facet slanting slightly upward. A 



' Fades dorsalls. ' Spiaa scapulae. ^ Acromion. 



