ANATOMY OF THE ANTHEOPOID APES. 189 



itself and adjacent muscles ; its tendon commences at the wrist, and is therefore rather 

 shorter than that of the extensor ossis metacarpi pollicis, but almost exactly of the same 

 thickness ; the two tendons run in very close contact ; it is inserted on to the base of 

 the metacarpal of the thumb on the inner side. 



(33) Pronator radii teres. — The origin of this muscle is much more distinctly double 

 than in the Orang ; its insertion on to the radius is chiefly tendinous, and measures 

 two and a half inches in length. 



(34) Palmaris longus. — This muscle is very slender, and ends in a tendon about half- 

 way down the arm ; towards its origin from the flexor condyle the muscle is not at all 

 distinct. Its tendon is continuous with a vertical tendinous sheet, from which fibres 

 of the flexor carpi radialis and of i\ie flexor suhlimis arise; at the wrist it is con- 

 tinuous with the very dense and stout palmar fascia. 



(35) Flexor carpi radialis. — It arises from the flexor condyle, from the septa between 

 itself and the pronator radii teres, flexor sublimis, and palmaris longus ; the muscle 

 becomes free about three inches in front of the wrist ; its tendon is visible upon the 

 under surface of the muscle, first of all about halfway down the arm ; the muscular 

 fibres cease only just at the wrist. It is inserted on to the base of the second 

 metacarpal. 



(36) Flexor carpi ulnaris. — The muscle arises from the flexor condyle and from a 

 considerable portion of the ulna, and from the septa between itself and adjacent muscles, 

 as well as from the fascia covering the arm ; it becomes tendinous only on the ventral 

 side, and is inserted principally on to the ulnar distal carpal (pisiform) ; it measures 

 half an inch in diameter at its insertion. 



(37) Flexor suhlimis {perforatus) digitorum. — The four muscular bellies which 

 together make up this muscle are quite separate from each other halfway down the 

 arm ; the undivided muscle arises from the flexor condyle, from the septa between 

 itself and adjacent muscles, and from the radius ; the part which arises from the radius 

 mainly belongs to the flexor of the third digit, which has the stoutest tendon, com- 

 mencing earlier than in the others upon the under surface of the muscle ; the actual 

 tendon itself of the fourth digit is the longest ; that supplying the little finger is very 

 much more slender than the rest; the tendons supplying digits iii., iv., and v. lie 

 superficially to the remaining tendon ; a muscular slip measuring three and a half 

 inches in length arises from a tendinous intersection upon that part of the flexor 

 sublimis belonging to the little finger, and is inserted on to the deep flexor tendons of 

 digit IV. by a short flat tendon of its own. 



(38) Flexor longus pollicis. — This muscle is very distinct from the next to be 

 described ; it arises chiefly from the radius and from the interosseous membrane, but 

 also from the septum between itself and the flexor carpi radialis ; its tendon com- 

 mences on the under surface of the muscle about halfway down the forearm; the 

 tendon is free from muscle on a line with the base of the thumb metacarpal ; at this 



