ANATOMY OF THE ANTHEOPOID APES. 209 



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and the triceps ; this septum is continuous with the dorso-epitrochlear ; posteriorly it 

 becomes a narrow ligament, inserted on to the flexor condyle of the humerus ; an inch 

 and a half from the distal extremity of the humerus the muscle becomes free, and, 

 curving over the joint, is inserted on to the ulna, being continuous also with the 

 ligament binding the humerus and ulna. On the outer face the insertion is muscular ; 

 on the inner face it is tendinous anteriorly, and also where it joins the aforesaid 

 ligament. 



(22) Anconwus is present, and looks lilie a continuation of the triceps. 



(23) Supinator radii longiis. — This is a large muscle ; it arises just in front of the 

 extensor carpi radialis longior, from the upper part of the external ridge of the 

 humerus ; anteriorly to this it is continuous with the fibres of the coraco-lrachialis, of 

 which it appears to be a continuation ; the origin from the bone measures an inch and 

 three-quarters in length. It is inserted by a flat broad tendon, two inches long, upon 

 a prominent ridge on the external border of the radius. 



(24) Extensor carpi radialis longior. — This muscle arises from the lower part of the 

 external condylar ridge of the humerus, just below the last muscle. Three inches 

 from its origin it becomes a tendon, which passes over the wrist in close connection 

 with the tendon of the next muscle, and is inserted on to the base of the metacarpal 

 ot the index ; just before its insertion it is reinforced by a thin tendon arising from the 

 extensor carpi radialis brevior. 



(25) Extensor carpi radialis brevior arises from the extensor condyle of the humerus 

 by a tendon common to it and the other extensors ; also from the fascia covering the 

 supinator brevis, and from the septum between itself and the extensor communis ; it 

 becomes entirely tendinous three inches from the wrist. At about an inch from the 

 wrist it gives ofi" a thin tendon which, running obliquely forwards, joins the tendon of 

 the extensor carpi radialis longior just before its insertion. The main tendon of the 

 present muscle, which is slightly broader th;in that of the " longior," is inserted into 

 the base of the metacarpal of the middle digit. 



(26) Extensor communis digitorum. — This muscle arises from the extensor condyle, 

 and lies between the extensor carin radialis brevior and the extensor minimi dic/iti, from 

 the septa between which muscles and itself it also arises ; about halfway down the 

 forearm it divides into four muscles, from each of which a tendon arises supplying 

 digits ii.-v. ; that supplying digit iv. gives off' a very thin tendon, which joins the deep 

 extensor of digit in. ; they are inserted over the first and second phalanges. 



(27) Extensor minimi digiti lies between the extensor communis digitorum and the 

 extensor carpi ulnaris; just before the wrist it divides into two, which join the tendons 

 of the extensor communis, which go to the fourth and fifth digits. 



(28) Extensor carpi ulnaris arises from the extensor condyle and from a considerable 

 length of the ulna ; the short thick tendon is inserted on to the outer side of the base 

 of the last metacarpal. 



VOL. XIII. — PAKT V. No. 5, Eebruary, 1893. 2 h 



