150 THE CAT. [CHAP. v. 



thickenings, and finally invests the bases of the digits. Near the 

 wrist it gives origin to the ulnar part of the flexor sublimis. 



Flexor sublimis digitormn or ' perforatus. This muscle consists of 

 two distinct parts, each of which is inseparably connected with another 

 muscle. 



The ulnar part of the flexor sublimis -arises from the ulnar side 

 of the palmaris longus close to the wrist. It ends in two tendons, 

 which go to the fourth and fifth digits respectively (Fig. 81, Fsd 1 ). 



Its radial part arises from the surface of the ulnar part of the 

 flexor profundus from the upper part of its tendon. It divides 

 into two small fleshy portions, the larger of which gives origin to 

 two delicate tendons which go to the index and third digits (Fsd 2 ). 



All these four tendons go to the second phalanx of their respec- 

 tive digits, each splitting (before its insertion) to allow a tendon of 

 the deep flexor (next to be described) to pass through, whence this 

 flexor receives its second above-given denomination. 



The second portion of the radial part of the muscle ends in a very 

 delicate tendon, which goes to the ulnar side of the pollex. 



The flexor profundus digitorum or flexor perf or ans. This is a very 

 complex muscle, which arises by five heads. 



(1.) The first of these arises from the internal condyle of the 

 humerus, in common with the third head and with the humeral 

 head of the flexor ulnaris. Passing down it ends in a tendon 

 which gives off superficially the radial part of the flexor sublimis, 

 while on its deep surface it receives the insertion of the mus- 

 cular fibres of the second part. Its tendon fuses with the main 

 tendon at the wrist. 



(2.) The second part, which is large and fleshy, arises from the 

 outer surface of the ulna from near the wrist nearly to the 

 end of the olecranon, and passing up at the olecranon inside both 

 the flexor carpi ulnaris and the fifth part of the triceps. It is 

 inserted into the deep surface of the tendons of the first part 

 of the flexor profundus. 



(3 ) The third part arises from the internal condyle, in common 

 with the first part, and is also connected with the fourth part 

 some little distance below its origin. It ends in a rather 

 delicate tendon, which joins the main tendon at the wrist. 

 (4.) The fourth part arises from the internal condyle, in common 

 with the flexor carpi radialis. It becomes connected with the 

 third part, and further down, ends in a rather strong tendon 

 which joins the main tendon at the same time as does that of 

 the third part. 



(5.) The fifth part arises from the flexor surface of the radius 



between the supinator brevis and pronator quadratus, and is 



inserted into the common tendon (Fig. 81, Fpd 5 ). 



The common tendon divides into five small tendons, which go to 



the distal phalanges of the five digits. Each of these tendons, except 



that to the pollex, passes through the split before mentioned as 



existing in each corresponding tendon of the flexor sublimis. It 



