POSTEEIOR TIBIAL GROUP. 251 



Relation. — Posteriorly with the gastrocnemius and flexor 

 perforatus ; anteriorly with the tibia ; internally with the flexor 

 pedis accessorius ; externally with the peroneus. 



Action. — To flex the phalanges, and assist in extending the 

 tarsal joint. 



FLEXOR PEDIS ACCESSORIUS. 



{Flexor Ohliq uus — Peroneo-iohalangeus. ) 



(Fig. 86. d.) 



This muscle is situated on the posterior part of the leg, be- 

 tween the popliteus and flexor pedis perforans. It is fleshy, with 

 numerous fibrous intersections, and inferiorly a terminal tendon. 



Origin. — From the external tuberosity of the tibia, and some- 

 times slightly from the fibula ; the tendon commences just above 

 the tarsal joint, and passes through a theca on its internal aspect. 



Insertion. — It joins the tendon of the flexor perforans at 

 about a third from its commencement. 



Relation. — Posteriorly with the gastrocnemius and flexor 

 perforatus ; anteriorly with the perforans, the popliteus, and the 

 posterior tibial artery. 



Action. — To assist the flexor pedis perforans. 



POPLITEUS. 



(Femoro-tibicdis Obliqmis. ) 

 (Fig. 86. a.) 



Situated at the back of the tibia, just below the stifle joint, 

 this muscle is triangular and fleshy, the fibres passing obliquely 

 downwards and inwards. 



Origin. — By a tendon from a fossa outside the external con- 

 dyle of the femur ; it is attached to the capsular ligament of the 

 stifle joint. 



Insertion. — The triangular surface on the supero-posterior j)art 

 of the tibia, and the upper portion of its internal border. 



Relation. — Posteriorly with the gastrocnemius and flexor 

 perforatus ; anteriorly with the tibia, the capsular ligament, and 

 the tibial vessels ; externally with the flexor pedis perforans and 

 accessorius ; internally with the biceps rotator, and tibial fascia. 



Action. — It flexes the leg, rotates it inwards, and tenses the 

 capsular ligament of the stifle joint. 



