372 Anatomy Applied to Medicine and Surgety. 



posterior surface of the fibula and from the adjoining in- 

 terosseous membrane ; into the base of the last phalanx of 

 the great toe and by a small slip into that part of the pre- 

 ceding muscle going to the second and third toes. Action. 

 It flexes the last and then the first phalanx of the great 

 toe; flexes, slightly, the anterior part of the foot 

 at the medio-tarsal joint, and, in addition, extends the 

 foot at the ankle. This muscle is of importance in walk- 

 ing, in which action it is strongly contracted so as to press 

 the great toe, which is the last to leave the ground in walk- 

 ing, firmly against the ground. Tibialis posticus. From 

 the tibia, between the upper part of the oblique line, above, 

 and the middle of the external border of the bone, below ; 

 from the upper two-thirds of the internal surface of the 

 fibula and from the interosseous membrane between these 

 origins ; into the tuberosity of the scaphoid, and, by off- 

 sets, into all the other tarsal bones, except the astragalus, 

 and into the bases of the second, third and fourth meta- 

 tarsal bones. Action. It extends the foot at the ankle 

 joint, inverts or raises its inner border, adducts the front 

 part, and, on account or by means of its tarsal attachments, 

 it assists in maintaining the arches of the foot. Nerves. 

 Since all these muscles extend the foot they are sup- 

 plied by the same nerve, viz., the posterior tibial. 



Bloodvessels. The posterior tibial artery passes 

 down the leg, beginning, above, at the lower border of 

 the popliteus muscle, and terminating, below, in the fossa 

 between the heel and the inner ankle. 



Relations. It lies on the tibialis posticus, the 

 flexor longus digitorum, the tibia and the back of ankle 

 joint, and is situated beneath the superficial and deep fas- 

 ciae and the gastrocnemius and soleus ; below, it runs par- 

 allel with the inner border of the tendo Achilles. The 

 posterior tibial nerve crosses it, and, therefore, in the upper 



