628 A MANUAL OF ANATOMY. 



culum tali ; for this distance the tendon is contained in a 

 fibrous canal lined with synovial membrane. It continues 

 forward above the tendon of the flexor longus digitorum, to 

 which it gives a slip, and passes to its insertion. 



Nerve Supply. The posterior tibial. 



Action. To flex the great toe, to flex the mediotarsal 

 joints of the foot, to extend the foot upon the leg. 



The two above muscles are intimately concerned in 

 walking and all allied acts ; by their contraction the integ- 

 rity of the arch of the foot is preserved. 



Tibialis Posticus. Figs. 130, 131. 



Origin. From the posterior surface of the tibia external 

 to the origin of the flexor longus digitorum, and extending 

 from the oblique line to the middle and lower thirds of the 

 shaft ; from the postero-internal surface of the fibula internal 

 to the origins of the soleus and the flexor longus hallucis, 

 and extending from the neck to the lower fourth of the 

 shaft ; from the posterior surface of the interosseous mem- 

 brane for its upper three-fourths ; from the intermuscular 

 septa on either side and from the surface of fascia covering 

 the three deep muscles of the leg. 



Insertion (see Foot). Into the tubercle of the scaphoid, 

 the os calcis (anterior part of the sustentaculum tali), 

 the under surface of the base of the first metatarsal, 

 three cuneiform and cuboid bones, by a broad expansion of 

 the tendon of the muscle which passes into the ligaments 

 which bind the bones of the foot together. The tendon 

 of the muscle passes behind the internal malleolus, being 

 the most anterior of the structures at this place. In this 

 course it is contained in a stout fibrous canal lined with 

 synovial membrane. 



Nerve Supply. The posterior tibial. 



