IIUMERUS. 



693 



** 



angular surface for tlie insertion of the deltoid muscle, and 

 about the same point an oblique vascular foramen. The pos- 

 terior surface is smooth, and covered by the triceps muscle. 



The upper or scapular extremity presents a smooth, hemi- 

 spherical surface, covered with cartilage, and called the 

 head. It articulates with the glenoid cavity FIG. 217. 

 of the scapula. Just below and around the 

 head there is a furrow or contraction of the 

 bone called its neck. It is rough and gives 

 attachment to the capsular ligament. Below 

 the neck the humerus swells into two pro- 

 cesses called tuberosities. They are two in 

 number, external and internal, or the greater 

 and lesser. The external presents three de- 

 pressions ; the anterior p , middle, and posterior^ 

 To the anterior the supra spinatus, to the 

 middle the infra spinatus, and to the posterior 

 the teres minor muscles are attached. The in- 

 ternal tuberosity gives insertion to the tendon 

 of the subscapularis. 



The inferior extremity of the humerus is, 

 flattened, and is bounded externally and inter- 

 nally by two ridges for the attachment of * 

 muscles and the intermuscular ligaments. These ridges 

 lead to the two projections called condyles. The internal 

 condyle is most prominent and has attached to it the inter- 

 nal lateral ligament, and the pronator and flexor muscles. 

 The external condyle, less prominent, gives attachment 

 to the external lateral ligament and to the supinator and 

 extensor muscles. Between these two condyles a smooth 

 articulating surface is observed, separated by a ridge. The 



FIG. 217 represents the anterior surface of the Humerus. a Shaft or body 

 of the Humerus. 6 Head, c Anatomical neck, d Greater tuberosity. e Lesser 

 tuberosity. / Bicipttal groove, g- Point of insertion for the pectoralis major. 

 h Internal bicipital ridge, i Point where the deltoid is inserted, j Nutritious 

 foramen, k Articular surface for the radius. I Articular surface for the ulna, 

 m External condyle. n Internal condyle. o p Condyloid ridges, q Lesser 

 sigmoid cavity. 



