ANTIBRACHIAL EEGION. 221 



CAPUT PARVUM. 



{Burner o-olecranius Internus.) 

 (Fig. 81. a.) 



Placed on the inner and mesian portion of the shaft of the 

 humerus, along the inferior border of the caput magnum, this 

 muscle is slender and triangular, with a fleshy origin. The fibres 

 pass obliquely backwards and downwards, terminating in two flat 

 tendons. 



Origin. — From the postero-internal part of the middle third 

 of the humerus, extending from the inner tubercle. 



Insertion. — To the inner part of the apex of the olecranon, 

 one tendon passing over a small groove before its insertion, which 

 is situated below the other one. 



Relation. — Superiorly with the caput magnum; externally 

 with the humerus, humeralis obliquus, and caput medium ; in- 

 ternally with the insertion of the coraco-humeralis, with the teres 

 internus, latissimus dorsi, and scapulo-ulnaris. 



Action.-^To extend the fcre-arm. 



ANCONEUS. 



(Humero-olecranius Parvus.) 

 (Fig. 80. e.) 



Situated at the back of the elbow joint, it is small, thick, and 

 almost entirely fleshy, filling up the space between the condyles 

 of the humerus, or the olecranon fossa. 



Origin. — From the borders of the fossa, chiefly the epi trochlea, 

 and the capsular ligament of the elbow joint. 



Insertion. — The antero-extemal part of the olecranon. 



Relation. — Posteriorly with the caput medium muscle ; ante- 

 riorly with the elbow joint and humerus. 



Action. — To tense the capsular ligament, and prevent it from 

 being crushed during extreme extension. 



ANTIBRACHIAL REGION. 



The muscles of this region, the fore-arm, cover the ulna and 

 radius, except on the inner aspect of the latter, where there is little 

 interposed between the skin and the bone ; they are divided into 



