132 



DISSECTION OF THE DOG 



m. extensor carpi idnaris j 



tn. extensor digiti quinti 



m. extensor digiti _ 

 tertii et quarti 



tn. extensor digit >rum_ 

 communis 



in. extensor pollicis longus 



el indicis proprius 



in. extensor carpi radialis 



-\\ — m. abductor pollicis longus 



the first phalanx, each tendon is further joined by the slender tendon of 

 an interosseous muscle. The short extensor and interosseous tendons 

 may blend before they unite with the common extensor tendons. 



M. EXTENSOR DIGITI 

 TERTII ET QUARTI : M. 

 EXTENSOR DIGITI QUINTI. 



— These two extensors of 

 the digits arise as a 

 common muscle from the 

 lateral epicondyle of the 

 humerus and the lateral 

 collateral ligament of the 

 elbow-joint. In the proxi- 

 mal third of the forearm, 

 the common mass divides 

 into two fleshy bellies, of 

 which that of the extensor 

 of the third and fourth 

 digits is the longer. The 

 tendon in which the 

 longer belly terminates 

 divides as the carpus 

 into two parts, which join 

 those tendons of the com- 

 mon extensor destined 

 for the third and fourth 

 digits. The very much 

 stronger tendon of the ex- 

 tensor of the fifth digit, 

 in like manner, joins the 

 common extensor slip 

 belonging to that digit. 



M. EXTENSOR CARPI 



ulnaris. — The ulnar ex- 

 tensor of the carpus forms 

 the extreme ulnar border 

 of the forearm. A flat- 

 tened and partly ten- 

 dinous belly takes origin 

 from the lateral epicon- 

 dyle of the humerus, 

 where it is closely asso- 



FlQ. 50.— Tendons on the dorsum of the manus. dated, with the anconeus. 



