ANTIBKACHIAL REGION. 221 



CAPUT PARVUM. 



{Humero-olecranius Internus. ) 

 (Fig. 81. a.) 



Placed on the inner and median 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 fore-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 epitrochlea, 

 and the capsular ligament of the elbow joint. 



Insertion. — The antero-external 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 



