DEEP MUSCLES OF THE BACK OF THE LEG. 193 



evert and partly divide the flexor hallucis after that muscle has 

 been examined ; then define the branches from its lower part to 

 the front of the leg, the outer side of the foot and the one that 

 joins the posterior tibial artery. 



DEEP GROUP OF MUSCLES (fig. 74). The deep muscles at the Four 

 back of the leg are four in number, viz., popliteus, flexor longus 

 hallucis, flexor longus digitorum, and tibialis posticus. The first of group : 

 these is close to the knee-joint ; it crosses the bones, and is covered 

 by a special aponeurosis. The flexors lie 011 the bones, the one of position and 

 the great toe resting on the fibula, and that of the other toes on the 

 tibia. And the tibialis covers the interosseous membrane. With 

 the exception of the popliteus, all enter the sole of the foot ; and destination, 

 they have a fleshy part parallel to the bones of the leg, and a 

 tendinous part beneath the tarsus. 



The POPLITEUS (fig. 74, A) arises by tendon, within the capsule Popliteus 

 of the knee-joint, from the front of an oblong depression on the ^Jthfn 

 outer surface of the external condyle of the femur (fig. 60, p. 157) knee-joint; 

 and within the capsule of the joint ; some fleshy fibres also arise 

 from the posterior ligament. The muscular fibres spread out, and inserted 

 are inserted into the tibia above the oblique line on the posterior m 

 surface, as well as into the aponeurosis covering them (fig. 73). 



The muscle rests on the tibia, and is covered by a fascia derived 

 in great part from the tendon of thesemimembranosus muscle : on it lie 

 the popliteal vessels and nerve, and the gastrocnemius and plantaris. 

 Along the upper border are the lower internal articular vessels and parts 

 nerve of the knee; and the lower border corresponds with the 

 attachment of the soleus on the tibia. The tendon of origin will be 

 seen in the dissection of the ligaments of the knee-joint. 



Action. The leg being free, the muscle bends the knee-joint, and use with 

 then rotates the tibia inwards. The popliteus is used especially in tl! 

 beginning the act of flexing the knee, as it produces the rotation special 

 inwards of the tibia (or outwards of the femur) without which that fu 

 movement cannot take place. 



The FLEXOR LOXGUS HALLUCIS (flexor longus pollicis pedis, fig. Flexor 

 74, F) arises below the soleus from the lower two-thirds of the pos- hSuISs is 

 terior surface of the fibula (fig. 73) ; from the intermuscular septum attached to 

 between it and the peronei muscles, and from the aponeurosis over 

 the tibialis. Inferiorly the tendon of the muscle enters a groove in 

 the astragalus, and crosses the sole of the foot to its insertion into 

 the great toe. 



Above, the muscle is covered by the soleus ; but below it is relations ; 

 superficial, and is in contact with the fascia. It lies on the fibula 

 and the lower end of the tibia, and conceals the peroneal vessels. 

 Along the inner side are the posterior tibial nerve and vessels ; 

 and contiguous to the outer margin, but separated by fascia, are 

 the peronei muscles. 



Action. The foot being unsupported, the flexor bends the last use, the 

 phalanx of the great toe, and then extends the ankle. f?2, being 



The foot resting on the ground, the muscle raises the heel ; and and 'fixed, 

 it draws the fibula backwards as the body rises from stooping. 



D.A. O 



