2o8 THE MUSCLES. 



insertions are identical with those of the flexor profundus digi- 

 torum of the hand. 



Relations. — Outer surface with the soleus (Fig. 90, o) and 

 plantaris (Fig. 91, /). Lateral border with the soleus, the 

 peroneus tertius (Fig. 90, ;-), and peroneus brevis (Fig. 90, s). 

 Medial border with the tibialis posterior (Fig. 91, o) and flexor 

 longus digitorum (Fig. 91, n). 



Action. — Flexor of the phalanges. 



(2) M. flexor longus digitorum (Fig. 91, n). 



Origin by muscle- and tendon-fibres from thfe > Lnitral sur- 

 face of the tibia over its proximal half between the oblique 

 rido-es ; by flesh)' fibres from an aponeurosis between it and the 

 tibialis posterior (Fig. 91, o), and by tendon from the medial 

 surface of the head of the fibula. At the junction of the middle 

 and distal thirds of the bone the muscle ends in a slender ten- 

 don which passes through the ventral groove on the medial 

 surface of the tibia and, curving onto the sole of the foot, 

 becomes attached to the medial border of the common tendon 

 described under the last. 



Relations. — Outer surface with the medial head of the gas- 

 trocnemius (Fig. 91, /') and with the superficial fascia. Inner 

 surface with the tibialis posterior (Fig. 91, ty). Medial border 

 at the proximal end with the popliteus (Fig. 92, k), lateral 

 border with the tibialis posterior (Fig. 91, ^), and flexor longus 

 hallucis (Fig. 91, ni). 



Action. — Flexor of the phalanges. 



M. tibialis posterior (Fig. 91, o). — A slender flat fusiform 

 muscle beneath the flexor longus digitorum and between it and 

 the flexor longus hallucis. 



Origin by fleshy fibres from nearly the whole medial surface 

 of the head of the fibula, from the inner surface of the apo- 

 neurosis between it and the flexor longus digitorum («), and by 

 a few fleshy fibres from the ventral surface of the tibia between 

 the oblique ridges. Some fibres may also arise from the outer 

 surface of the aponeurosis covering the flexor longus hallucis 

 (/;/). The muscle ends at about the middle of the tibia in a 

 slender flat tendon which passes parallel to the tendon of the 

 flexor longus digitorum (;/) through the dorsal groove on the 



