PLANTAR FASCIA. 255 



from the adjacent muscles, -whicli covers it. The muscular fibres end 

 in a strong- flat tendon, which, passing between the tibia and the long 

 flexor of the toes, turns forwards in a groove beneath the internal 

 malleolus, and is inserted into the tuberosity of the scaphoid bone. 



From its insertion, offsets of the tendon are prolonged forwards to 

 a.l the cuneiform bones, to the os cuboides, and to the bases of the 

 second, third, and fourth metatarsal liones ; and one thin process is 

 directed backwards to the sustentaculum tali. The tendon is covered 

 by a synovial membrane behind the malleolus. Close to its insertion, 

 where it lies against the astragalus, it contains a sesamoid fibro- 

 cartilage, which is occasionally converted into bone. 



delations. — The tibialis posticus is concealed in gi-eat part by the aponeiu'csis 

 prolonged over it from the muscles on eiLher side. Superiorly, -n'here it is not 

 covered by these muscles, it supports the posterior tibial and peroneal vessels. 



Viirictics. — These are rare. Several anatomists have described an occasional 

 muscle, which arises from the back of the tibia below the iiexor dig-itoram, and 

 is inserted into the capsule of the ankle-joint or into the ligamentum cruciatum. 

 This is the tensor of the capsule of the ankle-joint of Ilenle and Linliart, or the 

 tibialis secundus of Bahnsen. 



Nerves. — The gastrocnemius, plantai-is, soleus, and popliteus, are supplied with 

 branches from the mternal popliteal nerve. The flexor longus digitorum, flexor 

 longus pollicis and tibialis posticus derive tlieir neiTes from the posterior tibial. 



THE PLANTAR FASCIA AND MUSCLES. 



The superficial fascia of the sole of the foot resembles that of the 

 palm of the hand. It forms a thick cushion, especially over bony pro- 

 minences, and consists mainly of small lobules of fatty tissue bound 

 down by numerous fibrous bands which pass vertically from the skin to 

 the deep fascia. 



The deep plantar fascia, which is remarkably strong, is composed 

 of dense white glistening fibres, the greater number of which are 

 arranged in a longitudinal direction, and extend from the under surface of 

 the OS calcis forwards to the heads of the metatarsal bones. It presents 

 a central and two lateral portions, clearly marked off from each other 

 by two strong intermuscular septa, indicated on the surface by grooves. 

 The inner portion, thinner and looser than the others, invests the 

 abductor pollicis, and is often partly removed with the skin in dissec- 

 tion. It is continuous round the inner border of the foot with the dorsal 

 fascia and with the internal angular ligament. The outer part covers the 

 abductor minimi digiti, and is much stronger, particularly between the 

 outer tubercle of the calcaneum and the base of the fifth metatarsal bone, 

 between which points it forms a strong ligament. It is continuous 

 round the outer border of the foot with the dorsal fascia, and sends a thin 

 prolongation forwards over the insertion of the abductor and the short 

 flexor of the little toe. The central j)ortion, like the corresponding part 

 of the palmar fascia, is narrow behind, and becomes wider and thinner 

 towards the toes. At the back, where it is thickest, the fascia is 

 attached to the inner tubercle on the under surface of the calcaneum 

 immediately behind the origin of the flexor brevis digitorum, with 

 which muscle it is closely connected. Nearly opposite "the middle of 

 the metatarsal bones, this fascia, becoming broader and thinner as it 

 advances, begins to divide into five processes, one for each of the toes ; 

 and ii'om this point forwards to the base of the toes, numerous strong 



