THE MUSCLES OF THE OX — MUSCLES OF THE FACE 295 



MUSCLES OF THE METATARSUS AND DIGIT 



Extensor pedis brevis (M. extensor digitalis brevis). — This small muscle lies 

 in the angle of union of the long and lateral extensors of the digit. (Shown in 

 Fig. 201, but not marked.) 



Origin. — The outer tendon of the peroneus tertius, the middle annular liga- 

 ment, and the outer lateral ligament of the hock. 



Insertion. — The tendon of the anterior or long extensor. 



Action. — To assist the anterior or long extensor. 



Structure. — It is principally fleshy, having a superficial origin from the annular 

 ligament, and a deep one (by a thin tendon) from the outer tendon of the peroneus 

 tertius. The insertion is by a thin tendon. 



Relations. — Superficially, the skin and fascia and the tendons of the anterior 

 and lateral extensors; deeply, the joint capsule, the great metatarsal artery, and 

 the deep peroneal nerve. 



Blood-supply. — Great metatarsal artery. 



N^erve-supply. — Deep peroneal nerve. 



The interossei and lumbricales are arranged like those of the thoracic limb, 

 the only noticeable dift'erence being the greater development of the lumbricales in 

 the pelvic limb. 



THE MUSCLES OF THE OX 

 Muscles of the Face 



The panniculus is much more developed than in the horse, presenting as a 

 special feature the extensive frontalis muscle, which covers the frontal and nasal 

 regions. 



The orbicularis oris does not form a com^plete ring, the defect being in the 

 middle of the upper 11]). 



The levator nasolabialis is extensive, thin, and not very distinct from the 

 frontalis; it divides into two layers, betw^een which the levator labii superioris 

 proprius and the lateral dilator of the nostril pass. The superficial layer ends in 

 the nostril and upper lip, the deep layer on the accessory (lateral) nasal cartilages 

 and on the nasal process of the jiremaxilla. 



The levator labii superioris proprius arises on and before the facial tuberosity 

 and terminates by several tendons in the muzzle. It passes between the two 

 layers of the preceding muscle, blending in part with the deep layer. 



The zygomaticus is much stronger than in the horse. It arises on the masse- 

 teric fascia, and ends chiefly in the upper lip. 



The depressor labii superioris does not resemble the muscle of the same name 

 in the horse. It arises just in front of the facial tuberosity, and divides usually 

 into two branches, which terminate in a number of tendons that form a network 

 in the muzzle and upper lip. 



The incisivus inferior is a small, rounded muscle, which arises on the body of 

 the mandil^lo below the second and third incisors, and ends in the lower lip, 

 blending with the orbicularis. 



The depressor labii inferioris is thin, and does not extend as far backward 

 as in the horse; only the anterior end is distinct from the buccinator. 



The buccinator shows no marked variation, but its superficial layer is well 

 developed. 



The dilatator naris lateralis arises in front of the facial tuberosity, passes for- 



