260 ANATOMICAL TBCENOLOGT. 



Insertion. — At the epitrocMea the fleshy fibers are replaced by 

 a thin tendon which really forms part of the general antebrachial 

 fascia, and is continuous with the tendons of the pecto-antehracM- 

 alis ; so much of the fascia as belongs to this muscle is attached 

 along the proximal 10-15 mm. of the caudal border of the triangular 

 subcutaneous area upon the dorsal aspect of the olecranon. 



M. MBDITEICEPS. 



§ 683. Synonymy. — The liuman middle or scapular head of the triceps, G., A, 400, Q., 

 A, I, 307 ; " liceps-moyen," S.-D., A, II, 348 ; " long extenseur et gros extenseur de Vavant 

 hras," Ch., A, 373 ; the long and large extensor of the forearm, Ch. (FL), A, 358; second 

 'part of the triceps, Miv., B, 149. 



Figures. — Cephalic aspect (66, 67, 74) ; caudal aspect (73, 75) ; origin area (43). 



Posture. — At first the arm should rest upon its cephalic side, 

 but the posture must be changed several times during the dissection. 



Exposure. — By the reflection of the MM. latissimus, teres and 

 epitrocMearis. 



General Description. — Prismatic, from the glenoid third of the 

 glenoid border of the scapula to the olecranon. 



Dissection. — At the middle of its length the ventral border of 

 the muscle is indicated by the large nerve which lies between it and 

 the M. entotriceps. Let the scapula be flexed upon the brachium 

 so as to relax the muscle, and dissect from the caudal toward the 

 cephalic border along its entire length, as far as the epitrochlea. 



The cephalic surface is readily separable from the ectotriceps in 

 its proximal fourth ; but for the rest of its length it is united with 

 the dorsal border of that muscle by a strong fascia. In reflecting 

 the distal part, note the close union of both borders of the muscle 

 in its distal 5 mm., and the presence of a synovial sacJc over the 

 bifid tip of the olecranon. 



Origin. — By a short tendon, the outline of the section of which 

 is wedge-shaped, the base toward the glenoid end of the scapula 

 and the apex toward the gleno-vertebral angle. The line of origin 

 occupies nearly the glenoid third of the glenoid border, beginning 

 about 1 mm. from the glenoid fossa. 



Insertion. — By a short tendon upon the rounded tuberosity 

 which forms the dorsal angle of the olecranon ; the ventral border 

 of the tubercle is indicated by a slight transverse furrow. 



§ 683. Explanation of Fig. 75.— The muscles on the caudal 



