MUSCLES OF THE METATARSUS AND DIGIT 343 



Blood-supply. — Posterior tibial artery. 



Nerve-supply. — Tibial nerve. 



5. Popliteus (Fig. 298).— This thick, triangular muscle lies on the posterior 

 surface of the tibia above the popliteal line. 



Origin. — A small depression on the lateral epicondyle of the femur, close to 

 the articular surface and under the lateral hgament. 



Insertion. — A triangular area on the posterior surface of the tibia, proximal and 

 medial to the popliteal line; also the proximal half of the medial border and a 

 narrow adjacent part of the medial surface of the tibia. 



Actio7i. — To flex the femoro-tibial joint and to rotate the leg inward. 



Structure. — The strong tendon of origin lies at first under the lateral ligament, 

 and curves backward and inward over the lateral condyle of the tibia in contact 

 with the lateral meniscus; it is invested by a reflection of the synovial membrane 

 of the joint (Fig. 584). The tendon is succeeded by a thick triangular belly, the 

 fibers of which are directed medially in the proximal part, but incline downward 

 below. 



Relations. — Superficially, the fascia and skin, semitendinosus, gastrocnemius, 

 superficial flexor; deeply, the femoro-tibial joint, the tibia, the popliteal vessels 

 and their divisions. The saphenous vessels and nerve lie along the medial border 

 of the muscle, separated from it, however, by the deep fascia. 



Blood-supply. — Popliteal and posterior tibial arteries. 



Nerve-supply. — Tibial nerve. 



MUSCLES OF THE METATARSUS AND DIGIT 



Extensor digitalis brevis.^This small muscle lies in the angle of union of the 

 tendons of the long and lateral extensors of the digit. (Fig. 293.) 



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

 ment, and the lateral ligament of the hock. 



Insertion. — The tendon of the long extensor. 



Action. — To assist the 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 lateral tendon of the peroneus 

 tertius. The insertion is by a thin tendon. 



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

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

 the deep peroneal nerve. 



Blood-supply. — Great metatarsal artery. 



Nerve-supply. — Deep peroneal nerve. 



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

 the only noticeable difference being the greater development of the lumbricales in 

 the pelvic limb. 



THE MUSCLES OF THE OX 

 Muscles of the Face 



The cutaneus 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 complete ring, the defect being in the 

 middle of the upper lip. 



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



