CHAP, v.] THE CAT'S MUSCLES. IJl 



is on this account tliat the flexor profundus is also called the 

 "perforans." 



The hiiiibvicalcs are small, worm-like muscles (whence theirname), 

 which arise from the palmar surface of the deep flexor tendons of 

 the four outer digits, and are inserted into the sheaths of the 

 extensor tendons on the dorsal aspect of the digits as follows: — 



One arises from the radial side of the tendon going to the index 

 and is inserted into the radial side of the index. Another springs 

 from the palmar surface of the tendon of the modius, and goes to the 

 radial side of the medius ; the third springs from the palmar surface 

 of the tendons of the third and fourth digits, and goes to the radial 

 side of the fourth digit. The fourth and last arises from the radial 

 side of the tendon going to the fifth digit, and is implanted also into 

 the radial side of the fifth digit. 



The flexor carpi uliiari-s arises Ly two heads (separated by the 

 ulnar nerve), one from the inner condyle of the humerus, the other 

 from the inner side of the olecranon, almost to its very extremity, 

 so that it dips in under cover of the fifth part of the triceps. The 

 humeral belly of this muscle is intimately connected with that head 

 of the flexor profundus which gives origin to a part of the flexor 

 sublimis. The two heads continue separate a considerable distance, 

 and then unite and are inserted into the pisiforme and the fifth 

 metacarpal. 



Proiiafoi- qnadrcdu^i. — The fibres of this muscle extend obliquely 

 downwards from the ulna to the radius, on the deep flexor surfaces 

 of those bones for rather less than the lower half of each. 



Supinator loixjas. — This is a long and very slender muscle, which 

 arises high up, very much above the external condyle, from the 

 outer surface of the brachialis anticus, and from the middle third of 

 the outer surface of the humerus. It is inserted into the outer side 

 of the distal part of the radius (Fig. 81, >S7). 



The extenao)- carpi radialis loiKjior is also a long narrow muscle, 

 which arises from the supinator ridge below the origin of the muscle 

 last described, and is inserted into the dorsum of the second meta- 

 carpal. 



The extensor carpi radialis Irerior arises close beside and closely 

 connected with the last. Also long and narrow, it ends in a tendon, 

 which is implanted into the dorsum of the third metacarpal. 



Extensor communis digitorum. — This muscle takes origin from the 

 external condyle of the humerus, and is more or less divisible into 

 two parts. One part sends tendons to the second and third (or 

 second, third, and fourth) digits, and the other to the fourth and 

 fifth digits. Its tendons are inserted into the second and third 

 phalanges of each of the four ulnar digits. 



The extensor minimi di(jiti is of about the same size as the last 

 described muscle, arising in common with it and running down 

 beside it. It soon divides into three parts, whereof the first and 

 second are much more closely united together than they are to the 

 third part. The first two parts arise in front of and somewhat 



