HUMERUS. 69 



the antea spinatus muscle, while the posterior, or convexity of the 

 trochanter, the more prominent of the two, is covered with fibro- 

 cartilage, over which glides the tendon of the postea spinatus 

 muscle, which is inserted to a rough surface below the convexity. 

 The deltoid ridge joins this trochanter to the external tuberosity. 



The internal trochanter is divided into three roughened parts 

 — anterior, posterior, and inferior. The anterior forms the internal 

 boundary of the bicipital groove, and gives insertion to the inner 

 tendon of the antea spinatus, the posterior giving attachment 

 to the subscapularis, and the inferior to the pectoralis magnus 

 muscles. Between the anterior part of the internal and the 

 summit of the external trochanters is the hicipital groove, divided 

 by a middle prominence into two channels, the whole being 

 covered with fibro-cartilage ; through this groove the tendon of 

 the flexor brachii muscle plays. 



The distal extremity is smaller than the proximal, and smooth 

 to articulate with the radius and ulna ; its surface is convex, 

 and wider in front than behind. A deep groove, which extends 

 from the coronoid fossa in front, terminating in the condyloid or 

 olecranon fossa posteriorly, divides it into an internal condyle 

 and an external condyle or trochlea, the latter being the smaller, 

 and having a shallow furrow running across it from before back- 

 wards. At the side of the external condyle is a deep pit in 

 which the external lateral ligament is attached, and from which 

 a prominent ridge, the epitrochlea, extends upwards and gives 

 origin to the extensor metacarpi magnus, extensor pedis, and 

 flexor metacarpi externus muscles. 



Running upwards from the posterior part of the internal 

 condyle is a large eminence, the epicbndyle, from which the 

 flexor metacarpi internus, part of the medius, and the flexor pedis 

 perforans and perforatus muscles arise, and on its side is a small 

 eminence for the attachment of the internal lateral ligament. A 

 deep ovid fossa, the condyloid, which receives the olecranon 

 process of the ulna during the extension of the joint, separates 

 the epicondyle from the epitrochlea posteriorly ; and anteriorly, 

 just above the groove in the articular surface, is the shallow 

 coronoid fossa, which receives the coronoid process of the radius 

 during extreme flexion. 



