82 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM 



of the biceps. The "anatomical neck" is the part just behind 

 the head. 



The superior angle of the scapula is thin and rounded, and 

 gives attachment to some fibers of the levator anguli scapulae. 



The inferior angle is thick and rough posteriorly for the teres 

 major attachment, sometimes the latissimus dorsi. 



The superior border is shortest, and extends from the superior 

 angle down to the coracoid, at the base of which is the supra- 

 scapular or coracoscapidar notch. 



The axillary border is the thickest. Beneath the glerioid 

 fossa is a rough tubercle or ridge, infraglenoid, over an inch 

 long, for the long head of the triceps. On the ventral aspect of 

 this border is a longitudinal groove, from the lower part 

 of which the subscapular muscle rises in part. 



The vertebral border is the longest, and gives attachment 

 above the triangular surface at the apex of the spine to the 

 levator anguli muscle, opposite the triangular surface to the 

 rhomboideus minor, and below this to the rhomboideus major. 



THE BONE OF THE ARM 

 The Humerus 



The arm bone extends from the shoulder to the elbow. It 

 is divisible into an upper extremity, including head, neck, 

 great and small tuberosities, a shaft, and inferior extremity, 

 which includes condyles, epicondyles, and articular surface. 

 The head forms one-third of a sphere, but the margin is not 

 a true circle. The head is directed up, in, and a little back- 

 ward, and makes an angle of 140 degrees with the shaft. The 

 "anatomical neck" is the slight constriction at the circum- 

 ference of the articular surface; the "surgical neck" is below 

 the tuberosities. 



The great tuberosity is a thick projection starting up from 

 the external surface of the shaft. It is marked above by three 

 facets, the upper for the supraspinatus tendon, the next for 

 the infraspinatus, and the lowest for the teres minor, which 

 also is attached to the shaft to the extent of 1 inch. Internally 

 separated from this tuberosity by the bicipital groove (inter- 

 tubercular sulcus) is the small tuberosity, looking forward and 

 inward and giving attachment to the subscapularis. 



