292 



FASCIA AND MUSCLES OF THE HORSE 



2. Soleus (Fig. 201).— This muscle is very small in the horse. It lies immedi- 

 ately under the deep fascia, on the proximal half of the outer surface of the leg, 

 and is directed obliquely downward and backward. 

 Origin. — The head of the fibula. 



Insertion. — The tendon of the gastrocnemius, about the middle of the leg. 

 Action. — To assist the gastrocnemius. 



Structure. — It is a thin, fleshy band, about an inch (ca. 2 to 3 cm.) in width, 

 terminating on a thin tendon which fuses with that of the gastrocnemius.^ 



Relations. — Superficially, the skin, fascia, and peroneal nerve; deeply, the 



lateral extensor and deep 

 flexor. 



Blood-supply. — Poste- 

 rior tibial artery. 



Nerve-supply. — T i b i a 1 

 nerve. 



3. Superficial digital 

 flexor or flexor pedis per- 

 foratus (Figs. 199, 201, 203) 

 (M. flexor digitalis pecUs sub- 

 limis; superficial flexor of the 

 phalanges) . — The proximal 

 part of this muscle lies be- 

 tween and under cover of the 

 two heads of the gastrocne- 

 mius (Fig. 459). It con- 

 sists alm'ost entirely of a 

 strong tendon, the belly be- 

 ing very little developed. 



Origin. — The supracon- 

 dyloid fossa (Fossa plantaris) 

 of the femur. 



Insertion. — (1) The front 

 and sides of the tuber calcis; 

 (2) the eminences on the 

 proximal extremity of the 

 second phalanx, and the 

 distal extremity of the first 

 phalanx behind the lateral 

 ligament. 

 Action. — To flex the digit and extend the hock joint. On account of the ex- 

 ceedingly small amount of muscular tissue the action is to be regarded chiefly as a 

 mechanical effect, resulting from the action of other muscles on the stifle joint. 



Structure. — The origin is by means of a strong round tendon which is incom- 

 pletely covered with fleshy fibers as far as the upper third of the leg. It is pretty 

 intimately attached to the gastrocnemius, especially to the outer head. At the 

 distal third of the tibia it winds around the inner surface of the gastrocnemius 

 tendon, and then occupies a jwsition l^ehind the latter. At the point of the hock 

 it widens out, forming a sort of cap over the tuber calcis, detaching on either side 

 a strong band which is inserted into the tuber calcis with the tarsal tendon of the 

 ])iceps and semitendinosus. It then passes downward over the plantar (Calcaneo- 

 metatarsal) liganuMit, becomes narrower, and is arranged below as in the thoracic 

 limb. A large synovial bursa lies under the tendon from the distal fourth of the 



' The soleus may, therefore, be included with the two heads of the gastrocnemius under the 

 name triceps sura3. 



Fig. 204. — Cross-section of Left Leg of Horse; Section is Cut 

 A Little Above Middle of Region. 

 a, Tibia; b, fibula; c, tibialis anterior; d, peroneus tertius; 

 e, anterior or long digital extensor; /, lateral extensor; g, deep 

 head of deep flexor (flexor hallucis longus); h, inner head of deep 

 flexor (flexor accessorius s. digitoruni longus) ; /, superficial heatl of 

 deep flexor (tibialis posterior); h, popliteus; /, superficial flexor 

 tendon; m, gastrocnemius tendon; n, soleus; o, skin; p, anterior 

 tibial artery; q, superficial peroneal nerve; q' , deep peroneal nerve; 

 r, branch of q; s, posterior tibial artery; t, cutaneous nerve; u, 

 tibial nerve; r, recurrent tibial vein; w, saphenous artery; .r, saphe- 

 nous vein; y, branches of saphenous nerve. (After EUenberger, in 

 Leisering's .\tlas. ) 



