1 68 THE MUSCLES. 



Origin (Fig. 81, /z'). By a flat tendon trom the proximal 

 portion of the deltoid ridge and the distal border of the teres 

 minor tubercle. 



Insertion (Fig. 86, c) by a thin, flat tendon into the lateral 

 border of the dorsal surface of the ulna between a point oppo- 

 site the distal margin of the semilunar notch and the proximal 

 end of the olecranon. 



Relations. Lateral surface with the integument, and at the 

 proximal end with the spinodeltoid and acromiodeltoid (Fig. 

 75, e and f). Medial surface with the brachialis (Fig. 75, z), 

 the caput longum (g-}, the caput mediale, the brachioradialis (/), 

 the anconeus (Fig. 80, /), and the origins of the extensor carpi 

 radialis longus (Fig. 75, /), the extensor communis digitorum 

 (;;z), and the extensor digitorum lateralis (;z). 



Caput longum (anconeus longus) (Fig. 75, g; Fig. 68, k\ 

 Fig. 77, z ). A prismatic, fusiform mass connecting the scapula 

 with the olecranon. 



Origin (Fig. 78, z) by a thick, flat tendon from a triangular 

 area one or two centimeters long at the glenoid end of the 

 scapula on the glenoid border. The base of the area is about 

 one millimeter from the margin of the glenoid fossa. 



Insertion (Fig. 86, ^). The muscle ends in a thick tendon 

 which passes over the bifurcated ventral end of the olecranon 

 and is inserted upon the rounded tuberosity which forms the 

 dorsal angle of the olecranon. 



Relations. Lateral surface with the caput laterale (Fig. 

 75, /z), a portion of the caput mediale (Fig. 77, j and ), the 

 spinodeltoid (Fig. 75, e), the infraspinatus (Fig. 75, c), and 

 the integument. Medial surface with the epitrochlearis (Fig. 

 65, r) and the conjoined portions of the latissimus dorsi and 

 teres major (Fig. 79, d'}. Ventral border with the caput 

 mediale (Fig. 77, / and k}. 



Caput mediale. The medial head consists of three portions 



(Fig- 79. g, /',/) 



(i) The long portion (anconeus posterior) (Fig. 77, /; Fig. 



79 g', Fig. 8o,/). 



Origin (Fig. 83, e] from a triangular area on the dorsal sur- 

 face of the humeral shaft. The base of the area is against the 



