324 THE MUSCLES OF THE DOG 



The pronator quadra tus consists of fibers which cross the inner surface of the 

 interosseous hganient of the forearm, except at the two extremities of the latter. 

 It is attached to the inner l^order of the uhia and the anterior surface of the radius. 

 It rotates the forearm inward (pronation). 



The palmaris brevis (?) is a very small muscle, which arises on the tendon 

 of the superficial digital flexor for the fifth digit, and is inserted at the fifth meta- 

 carpo-phalangeal joint into the sheath and annular ligament of the deep flexor. 



The lumbricales are three very delicate muscles, which arise on the tendons 

 of the deep flexor, and are inserted into the first phalanges of the third, fourth, 

 and fifth digits. 



The abductor pollicis brevis et opponens poUicis, a 'very small pale muscle, 

 arises on the fibrous band which connects the superficial flexor tendon with the 

 inner carpal sesamoid, and ends on the cUstal end of the first metacarpal bone and 

 the first phalanx of the first digit. It abducts the first digit.^ 



The flexor pollicis brevis arises on the posterior carpal ligament over the second 

 metacarpal bone, and ends on the volar sesamoid of the first digit. 



The adductor pollicis, situated externally to the preceding, is the largest of 

 the thumb muscles. It arises between the preceding and the second interosseous 

 muscle, and is inserted into the first phalanx of the first digit. 



The adductor digit! secundi is situated between the second interosseous 

 muscle and the adductor cUgiti quinti. It arises on the carpal ligament, and ends 

 on the first phalanx of the second digit. 



The adductor digiti quinti arises close to the preceding muscle, and passes 

 outward to end on the first phalanx of the fifth digit. 



The flexor digiti quinti arises on the ligament connecting the accessory carpal 

 to the third and fourth metacarpal bones, crosses the corresponding interosseous 

 muscle, and ends on the fifth digit with the next muscle. 



The abductor digiti quinti is larger than the two preceding muscles; it arises 

 on the accessory carpal bone, and ends on the outer sesamoid of the fifth digit and 

 on the lateral ligament. 



There are four interossei which lie on the volar (posterior) surface of the meta- 

 carpus. They are well developed and fleshy. They arise on the distal row of the 

 carpus and on the proximal ends of the metacarpals. Each divides distally into 

 two branches, which are inserted by small tendons on the corresponding sesamoid 

 bones, and detach slips to the extensor tendons. 



Muscles of the Neck 



The sterno-cephalicus is well developed. It arises on the manubrium sterni 

 and ends on the mastoid process, blending with the cleido-cervicalis. 



The scalenus ventralis (s. primse costse) arises on the last four cervical trans- 

 verse processes, and is inserted into the first rib. 



The scalenus dorsalis (s. supracostalis) is large. Anteriorly it blends with the 

 preceding muscle, while posteriorly it divides into two parts. The upper part is 

 inserted on the third and fourth ribs, the lower part by a long, thin tendon on the 

 eighth rib. 



The longus colli resembles that of the horse. 



The rectus capitis anterior major arises on the transverse processes of the second 

 to the sixth cervical vortel)np and ends as in the horse. The rectus minor and 

 lateralis resoml^le those of the horse. 



The intertransversales resemble those of the ox. 



The splenius is strong and extensive. It arises on the first four or five thoracic 



1 Movements of individual digits are specified with regard to the axis of the manus (hand, 

 paw), and not to the median plane of the body. 



