THE MUSCLES OF THE LEG AND FOOT 



337 



l7isertion.—{l) The ridge on the front of the proximal end of the large meta- 

 tarsal bone; (2) the first and second tarsal bones. 



Action. — To flex the hock joint. 



Structure.— The origin is fleshy, and forms a groove in which he the common 

 tendon of the long extensor and peroneus tertius and a synovial pouch which de- 

 scends from the femoro-tibial joint. Many superficial fibers arise from the deep 

 fascia at the proximal part of the leg and thus from the tibial crest. Passing down- 

 ward on the tibia, the belly is united by tendinous and fleshy fibers with the per- 

 oneus tertius, and terminates close to the tarsus in a point on the tendon of inser- 



FiQ. 294. — Injected Synovial Sheaths and Burs^ 

 OF Tarsal Region of Horse; AIedial View. 

 a. Synovial sheath of peroneus tertius and tibialis 

 anterior; h, bursa under medial (cunean) tendon of 

 tibialis anterior ; c, synovial sheath of flexor longus ; 

 d, tar.sal sheath of deep flexor; e, e', bursa under 

 superficfal flexor tendon; /, /', tibio-tarsal joint capsule; 

 1, long extensor; £, tibialis anterior; £', medial (cun- 

 ean) tendon of £; 3, flexor longus; 4i deep digital 

 flexor; 5, superficial flexor tendon ; G, gaatrocnemius 

 tendon; 7, tibia; S, tarsus; 9, tuber calcis; 10, large 

 metatarsal bone ; 11, medial small metatarsal bone ; 

 IS, 12', fascial bands. (After Ellenberger, in Leisering's 

 Atlas.) 



Fig. 295. — Injected Synovial Sheaths and Burs^ 

 OF Tarsal Region of Horse; Lateral ^'^iew. 

 a. Synovial sheath of long digital extensor; h, 

 synovial sheath of lateral digital extensor; c, c' , bursa 

 under superficial flexor tendon; d, capsule of hock joint; 

 U long extensor; 2, lateral extensor; 3, 3, 3, annular 

 ligaments; 4, deep digital flexor; 6, tendon of gastroc- 

 nemius; 6, superficial flexor tendon; 7, tibia; S, tarsus; 

 9, tuber calcis; 10, metatarsus. (After Ellenberger, 

 in Ijeisering's Atlas.) 



tion. The latter emerges between the branches of the peroneus tertius and bi- 

 furcates, the anterior branch being inserted into the large metatarsal bone, the 

 medial one into the first tarsal bone. The tendon is provided with a synovial sheath 

 at its emergence, and a bursa is interposed between the medial branch and the 

 medial ligament of the hock,^ 



Relations. — Superficially, the long and lateral extensors, the peroneus tertius, 

 and the deep peroneal nerve; deeply, the tibia, the deep flexor, and the anterior 

 tibial vessels. 



^ In surgical works the medial branch is termed the cunean tendon; it is sometimes resected 

 for the relief of bone spavin. 

 22 



