THE LOWER EXTREMITY, POSTERIOR. 627 



They will be described at this time however, and the 

 student can review them after the foot has been dissected. 



Flexor Longus Digitorum. Figs. 130, 131, 133. 



Origin. From the posterior surface of the tibia, extend- 

 ing from the oblique line to the junction of the middle and 

 lower thirds of the bone, from the deep fascia which covers 

 the muscle, and from the intermuscular septum. 



Insertion (see Dissection of Foot). Into the bases of 

 the last phalanges of the four outer toes. 



The tendon of the muscle occupies a special fibrous canal 

 lined with synovial membrane behind the internal malleolus 

 (being posterior to the tendon for the tibialis posticus). 

 Turning forward into the foot the tendon crosses below 

 that for the flexor longus hallucis, to which it is connected 

 by a fibrous band, then receives the insertion of the flexor 

 accessorius and divides into the four terminal tendons ; they 

 then pass through a button-hole slit in the tendons of the 

 short flexor and on to their insertion. (See the Lumbri- 

 cales. 



Nerve Supply. The posterior tibial. 



Action. To flex the toes, beginning with the last pha- 

 langes and passing backward, to flex the joints of the foot 

 (mediotarsal), to extend the foot. 



Flexor Longus Hallucis (Pollicis). Figs. 130, 131, 133. 



Origin. From the posterior (and internal) surface of the 

 fibula for its lower two-thirds, from the deep surface of the 

 fascia which covers the muscle, from the intermuscular 

 septa on either side. 



Insertion (see Dissection of Foot). Into the base of 

 the last phalanx of the great toe. 



The tendon of this muscle slightly grooves the back of 

 the tibia and astragalus, passes forward under the sustenta- 



