BONES OF THE ARM. 45 



Into it is inserted I muscle, the pectoralis minor; the coraco-brachialis, 

 and the short head of the biceps arise from it by a common tendon ; and 3 

 ligaments are attached to it, the conoid, trapezoid, and coraco-acromial. 

 THE SUPERIOR BORDER presents the 



Suprascaptdar Notch, converted into a foramen for the suprascapular nerve 



by the transverse ligament, over which passes the suprascapular artery. 



The omo-hyoid muscle is attached to the border just internal to the 



notch. 

 THE AXILLARY BORDER is the thickest, and presents a 



Rough Surface, for the long head of the triceps muscle, just below the 



glenoid cavity. 



Groove, the origin of a part of the subscapularis muscle. 

 THE VERTEBRAL BORDER Is the longest, and presents an 

 Anterior Lip, for the attachment of the serratus magnus. 

 Posterior Lip, for the supra- and infra-spinatus muscles. 

 Interspace, between the lips, for the levator anguli scapulae, the rhomboideus 



minor, and the fibrous arch of the rhomboideus major muscles. 

 OTHER POINTS of interest on the bone are the 



Superior Angle, affords attachment to part of the serratus magnus, levator 



anguli scapulae, and supra-spinatus muscles. 

 Inferior Angle, affords attachment to part of the serratus magnus and 



teres major muscles, and occasionally to a few fibres of the latissimus 



dorsi. 

 Glenoid Cavity, at the external angle or head of the bone, a shallow 



cavity for the reception of the head of the humerus. It is deepened by 



the glenoid ligament which is attached around its margin; and at its 



upper part gives origin to the long head of the biceps flexor cubiti 



muscle. 

 Neck, is the contracted part of the bone behind the glenoid cavity ; from 



it arises the anterior root of the coracoid process. 



THE ARM. 



Describe the Humerus. It is the only bone in the arm, and articulates 

 with the scapula above, and with the ulna and radius below. It presents the 

 lollowing points, viz. 



Headp is nearly hemispherical, and smooth for articulation with a gle- 

 noid cavity of the scapula. 

 Anatomical Neckf is a constriction in the bone, just below the head, for the 



attachment of the capsular ligament. 



Greater Tuberosity,d has 3 small facets for the insertions of the supra- 

 spinatus, infraspinatus, and teres minor muscles. 



