ANATOMY OF THE ANTHEOPOID APES. 193 



away. It is inserted on to the inner condyle of the femur. The second part of the 

 adductor magnus arises below the first head and the gracilis from the symphysis pubis 

 and from the ischium ; the line of origin extends from close to the anterior extremity 

 of the symphysis back to a point upon the ischium corresponding to about the middle 

 of the origin of the first half of the adductor magnus; it arises not only from the bone 

 but from the septa between itself and the posterior head of the adductor hrevis and 

 obturator interims ; at about an inch from its insertion it is joined by the adductor 

 longus. The insertion of the muscle upon the femur extends from the end of the first 

 third of the bone up to its very extremity ; on the inner side, where the insertion is 

 common to it and the adductor longus, the muscle is strongly tendinous; on the outer 

 side the attachment is muscular and formed by coarsely fasciculate fibres. 



(21) Tibialis amicus. — This muscle is formed of two distinct parts, which, however, 

 originate in common ; the two tendons pass close together below the ligament 

 connecting the astragalus with the first metatarsal ; the hinder of the two tendons, 

 which is the shortest, is inserted on to the cuneiform bone ; the anterior tendon is 

 inserted, in common with the astragalo-metatarsal ligament, on to the proximal end of 

 the first metacarpal. 



(22) Extensor proprius hallucis. — This muscle arises from the fibula, from the- 

 interosseous ligament, and from the septa between itself and the adjacent muscles ; it 

 becomes entirely tendinous just at the astragalo-metatarsal ligament, underneath which 

 it passes, and, running along the upperside of the hallux, is inserted on to the distal 

 phalanx. 



(23) Extensor longus digitorum pedis. — The muscle arises from the fibula, from the 

 interosseous membrane, from the fascia covering the leg, and from the septa between 

 itself and the tibialis anticus, extensor propius hallucis, and peronceus tertius. The 

 muscle becomes free about two inches in front of the ankle. The tendons of insertion 

 are visible upon the upper surface of the muscle about an inch before they become free 

 from muscular fibres. In the middle of the ankle the muscle splits into two : one 

 division is entirely tendinous, the other is invested on the lower side with muscle for a 

 distance of about an inch beyond the division. The front tendon supplies the second and 

 third digits; it divides rather beyond the middle of the metacarpal into two tendons, 

 of which that supplying digit ii. is rather less than half the diameter of that supplying 

 digit III. The second division of the muscle again divides, just at the commencement 

 of the metatarsal region, into two equally sized tendons, which are each as large as the 

 tendon of digit iii. ; they supply digits iv. and v.; in every case the tendons are inserted 

 on to the terminal of the phalanx of the digit. 



(24) Extensor brevis digitorum consists of four muscular slips, which supply the 

 thumb and the next three digits ; their tendons join the long extensors of the digits 

 just at the commencement of the first phalanx ; the four muscles arise in common from 

 the OS calcis, but they become almost immediately distinguishable into the four slips ; 



VOL. XIII. — PAET V. No. 3. — February, 1893. 2 f 



