THE HUMERUS 



147 



Upper extremity. — The head forms a nearly hemispherical articular surface, 

 cartilage-clad in the recent state and directed upward, medially, and backward 

 toward the glenoid cavity. Below the head the bone is rough and somewhat 

 constricted, constituting the anatomical neck, best marked superiorly, where it 

 forms a groove separating the articular surface from the two tuberosities. The 

 circumference of the neck gives attachment to the capsule of the shoulder-joint 

 and the gleno-humeral folds, the upper of which is!received into a depression near 

 the top of the intertubercular (bicipital) groove. The lowest part of the capsule 



Fig. 175. — -Ihe i^eft Humerus. (Posterior view.) 



Articular capsule- 

 Infraspinatus- 



*., 



Teres minor - 



Triceps (lateral head)- 



Groove for radial nerve- 



Triceps (medial head)- 



Articular capsule. 

 Olecranon fossa- 

 Lateral epicondyle- 

 Anconeus and radial collateral ligament - 



'^:-k:^^ 



— Medial epicondyle 



Groove for ulnar nerve 

 Flexor carpi ulnaris 



descends upon the humerus some distance from the articular margin. Laterally 

 and in front of the head are the two tuberosities, separated by a deep furrow. The 

 greater tuberosity [tuberculum majus], lateral in position and reaching higher than 

 the lesser tuberosity [tuberculum minus], is marked by three facets for the 

 insertion of muscles: an upper one for the supraspinatus, a middle for the in- 



