Sole of Foot 501 



three pieces, of which the median is the strongest, and divides into 

 five slips which join the sheath of the flexor tendons of each toe. 

 These slips are strengthened by transverse fibres, under cover of 

 which pass the digital vessels and nerves. The lateral pieces of the 

 fascia blend with the middle piece, and with the deep fascia on the 

 dorsum of the foot. The outer piece covers the abductor minimi 

 digiti and extends to the base of the fifth metatarsal bone. The inner 

 piece covers the abductor hallucis. 



Uses of the plantar fascia. It strengthens the transverse as 

 well as the antero-posterior arches of the foot. It gives origin to the 

 three muscles in the superficial layer, the middle one being the flexor 

 brevis digitorum. It protects these muscles and the plantar vessels 

 and nerves, as when the bather treads on a broken bottle or a jagged 

 flint. (In company with other plantar structures, the fascia yields in 

 the case of flat-foot.) 



The three muscles in the superficial layer of the sole are the abduc- 

 tors hallucis and minimi digiti, with the flexor brevis digitorum be- 

 tween them. They all arise from the deep fascia, os calcis, and 

 inter-muscular septa. The abductors are inserted into the base of 

 the first phalanx of the great and little toes, and the flexor brevis 

 digitorum is inserted, like the flexor sublimis in the hand (p. 272), 

 into the sides of the penultimate phalanges of the four lesser toes, its 

 tendons being pierced by those of the long flexor. 



Tarsal ligaments. The long plantar ligament passes from the 

 under surface of the os calcis to the ridge on the under surface of the 

 cuboid, converting the groove for the tendon of the peroneus longus 

 into a tunnel. It then spreads into the bases of the second, third, and 

 fourth metatarsal bones. The short plantar runs from the under and 

 anterior part of the os calcis to the cuboid behind the groove. 



The internal calcaneo-cuboid is a short, strong band between the 

 inner and dorsal aspects of the bones. It forms the outer limb of the 

 V-shaped union between the first and second rows of the tarsus, the 

 inner limb being the superior calcaneo-scaphoid ligament, which 

 passes on to the dorsal surface of the scaphoid. 



The inferior calcaneo-scaphoid ligament is a broad, strong band 

 between the sustentaculum tali and the tuberosity of the scaphoid. 

 The tendon of the tibialis posticus passes like a strap beneath it. Its 

 upper surface is lined by the synovial membrane from between the 

 astragalus and os calcis, and supports the head of the astragalus. 

 The front of the deltoid ligament blends with and supports it. It 

 is sometimes called the ' spring ligament/ and it is one of the first 

 structures to give way in flat-foot. 



All these ligaments are necessarily divided in Chopart's amputa- 

 tion, which passes through the transverse tarsal joint. 



The bony arches of the foot. If the foot were a solid piece of 

 bone it would be very liable to fracture ; it would, moreover, possess 



