FlG. 23. 



) ANATOMY. 



Lesser Tuberosityf on the inner side of the bone, gives insertion to the 



subscapularis muscle. 



Bicipital Groove,/ lies vertically between the tuberosities for the upper third 

 of the bone, and lodges the tendon of the long head of the biceps flexor 

 cubiti. Into its inner or posterior lip h are inserted the teres major and 

 latissimus dorsi muscles, while its outer or anterior lip" receives the in- 

 sertion of the tendon of the pectoralis major, which covers the groove. 



Surgical Neck, is situated immediately below the tuberosi- 

 ties, and is a slight constriction in the upper part of the 

 shaft. 

 Shaft," is cylindrical above, prismatic and flattened below. 



Rough Surface,*- for the insertion of the deltoid* muscle, 

 about the middle of the external surface of the shaft. 



Musculo-spiral Groove, lodging the musculo-spiral nerve, 

 and the superior profunda artery, is situated on the pos- 

 terior surface of the shaft, separating the origins of the 

 outer and inner heads of the triceps muscle. 

 Orificej of the nutrient canal, about the middle of the 



shaft. 



Condyloid Ridges op internal and external, arising from 

 the respective condyles, extending upwards along the 

 shaft. 



External Condyle, gives attachment to the external 

 lateral ligament and the extensor and supinator group 

 of muscles. 



Internal Condylen lower and more prominent than the 

 other, gives attachment to the internal lateral ligament 

 and the flexor and pronator group of muscles of the 

 fore-arm. 

 Radial Headfi forms the external part of the inferior articular surface ; for 



articulation with the radius. 



Trochlear Surface,l articulates with the greater sigmoid cavity of the ulna ; 

 is a deep depression between two borders, and extends from the anterior 

 to the posterior surface of the bone. 

 Coronoid Fossatf in front of the trochlea, receives the coronoid process of 



the ulna when the fore-arm is flexed. 



Olecranon Fossa, behind the trochlea, receives the tip of the olecranon pro- 

 cess, when the fore-arm is extended. 



