340 



FASCIA AND MUSCLES OF THE HORSE 



the middle third of the posterior surface and the upper part of the lateral border of 

 the tibia, the posterior border of the fibula, and the interosseous ligament. 



Insertion.— The semilunar crest and the adjacent surface of the cartilage of 

 the third phalanx. 



Action. — To flex the digit and to extend the hock joint. 



Structure.— {\) The medial head is termed the long digital flexor (M. flexor 

 digitahs longus s. flexor accessorius) ; it is easily isolated (Figs. 298, 584). It has a 

 fusiform belly, which crosses the leg obliquely and lies in a groove formed by the 



Pcroucus tertius 



Long digital 

 extensor 



Supcrficiol peroneal . !"^< 



nerve jR§ 



Intennnxcular- -^^'^ 



septum 



Lateral digital 



e.elensor 



Intermuscular \ 



septum 



Flexor hallucis 



Tibialis posterior 

 Soleus 



Lateral head of gastroc- 

 nemius 



Recurrent tarsal vein 



Tibialis anterior 



Cutaueous hranchof 

 saphenous nerve 



\ Saphenous vessels 

 and nerve 



Popliteus 



Flexor digitalis longus 



Vein 



Tibial nerve 

 Superficial digital flexor 



Medial head of gastroc- 

 nemius 



Fig. 297. — Cross-section of Left Leg of Horse. 

 The section is cut aboiifc the junction of the proximal and middle thirds of the region. 1, Anterior tibial vessels; 

 2, deep peroneal nerve; 3, fibula; 4, posterior tibial vessels; .5, recurrent tibial vessels. X cutaneous branch of the 

 saphenous nerve is shown medial to the popliteus, but is not marked. 



other heads and the popliteus. This terminates near the lower third of the tibia 

 on a round tendon which descends in a canal in the medial ligament of the hock, 

 and joins the common tendon about a third of the way down the metatarsus. In 

 its course over the medial surface of the hock the tendon is provided with a syno- 

 vial sheath which extends from the distal fourth of the tibia to the junction with 

 the principal tendon. (2) The superficial head is the tibiaUs posterior (M. tibialis 

 posterior); it is onty partially separable from the deep head. It has a flattened 

 belly, terminating near the distal third of the tibia on a flat tendon which soon fuses 



