MUSCLHS Ol- TUB PELyiC LIMBS. 205 



is called extension in the foot is analogous to what is called 

 flexion in the hand, so that the extensors of the foot are most 

 readily to be compared with the flexors of the hand.) 



M. plantaris (Fig. 90, /; Fig. 91, /). — -A fusiform muscle 

 covered distally by the gastrocnemius, but appearing between 

 the two heads of the gastrocnemius at their proximal ends 

 (Fig. 90, /). 



Origin by a strong tendon from the middle of the lateral 

 border of the patella and by fleshy fibres from the ventral 

 border of the lateral sesamoid. 



The patellar tendon ends in a flattened head which passes 

 ventrad over the lateral epicondyle of the femur and then 

 curves distad ; it is closely united with the lateral head of the 

 gastrocnemius. The muscle ends in a thick tendon which 

 passes through a sheath formed by the tendons of the gastroc- 

 nemius and soleus, and the fascia of the shank. The tendon 

 passes over the grooved proximal end of the calcaneus onto its 

 ventral surface. It is held in place against the groove by two 

 sheets of aponeurosis, which leave the tendon on either side for 

 a distance of more than a centimeter and are attached to the 

 lateral surfaces of the calcaneus at its proximal end. Lateral 

 motion is thus hindered, while longitudinal motion is permitted. 



Between this tendon and the tendon of Achilles is a synovial 

 bursa which aids the gliding movement of the tendon. In the 

 sole of the foot opposite the distal end of the calcaneus the 

 tendon broadens and ends in the flexor brevis digitorum (pedis 

 perforatus) muscle, which might also be considered as a second 

 part of the plantaris. In man the plantaris is inserted into the 

 calcaneus along with the gastrocnemius. 



Relations. — The muscle is covered throughout by the two 

 heads of the gastrocnemius (Fig. 90, in\ Fig. 91, k), except 

 at the proximal end (Fig. 90, /), where it is in contact with the 

 integument. Inner surface in relation with the popliteus (Fig. 

 92, k), the soleus (Fig. 90, 6), the flexor longus digitorum 

 (Fig. 91, «), and flexor longus hallucis (Fig. 91, ;//). 



M. soleus (Fig. 90, 6). — A flat fusiform muscle lying 

 beneath the plantaris. 



Origin by muscle-fibres from the lateral surface of the head 



