THE FOOT 



1467 



mentioned toes. The sural nerve runs with the small saphenous vein below the 

 malleolus, and supphes all the lateral border of the foot and the lateral side of 

 the little toe. The saphenous nerve, coursing with the great saphenous vein in 

 front of the medial malleolus, supplies the medial border of the foot as far as the 

 middle of the instep. The cutaneous nerves to the sole (from the medial calcaneal, 

 medial, and lateral plantar) are shown in fig. 1180. 



Plantar arteries. — The line of the medial would be one drawn from the bifur- 

 cation of the posterior tibial, or about midway between the tip of the medial mal- 

 leolus and the medial border of the heel, to the middle of the plantar surface of the 

 great toe. The course of the lateral plantar runs in a line drawn from the bifur- 

 cation, first obhquely across the foot to a point a httle media) to the medial side of 

 the base of the fifth metatarsal, and thence obliquely across the foot till it reaches 

 the first space and joins with a communicating branch from the dorsal artery. It 

 thus crosses the foot twice. In the first part, it is more superficial, in the second 



Fig. 1181. — Longitudinal Section of Foot. (One-third.) (Braune.) 



Tendo Achillis 

 Posterior tibial vessels 

 Talus and nerve 



Navicular 

 First cuneiform 



Extensor hallucis longus 



Flexor hallucis longus 



Flexor hallucis brevis 



Lumbricalis 



Calcaneus 

 Abductor digiti quinti 

 Lateral plantar vessels and nerve 



Quadratus plantae 

 Flexor digitorum brevis | Flexor digitorum communis 

 Medial plantar nerve 



very deep; it here forms the plantar arch, and is only separated from the bases of 

 the metatarsals by the interossei. 



The anastomosing branches about the ankle-joint are shown in figs. 1170 

 and 1171. 



Tarsal bones. — The chief surgical points about these is the frequency with which they are 

 diseased and their changes in talipes. Frequency of disease. — This is explained, chiefly, 

 by their delicate structure and the fact that on the aspect in which they are most exposed to 

 injury the soft parts are scanty. Disease once started, often by slight injury, finds in the ter- 

 minal circulation of the parts, and the frequent want of rest, other contributing causes. The 

 numerous and complicated synovial membranes mentioned above explain the extension of the 

 disease. The calcaneus is the only bone in which mischief is likely to remain limited. The 

 presence of an epiphysis to this bone appearing about the age of ten and joining at puberty 

 is to be remembered as a starting-point of disease here. Talipes. — To take one instance, a case 

 of talipes equino-varus, of congenital origin and confii-med degree, the following are the chief 

 structural changes which should have been obviated and now have to be met, given briefly. 

 Calcaneus. — This is elevated posteriorly, and rotated so that its long axis is directed obliquely 

 medially. Talus. — The inclination of the neck medially is much increased, and the whole bone 

 protruded from the ankle-joint. According to some, the neck is increased in length. Navicular. 

 — This is displaced medially so that it articulates with the medial side of the head of the talus, 

 and its tuberosity may form a facet on the medial malleolus. Cuboid. — The dorsal surface of 

 this is displaced downward, and bears much of the pressure in walking. Tendons. — Those 

 chiefly shortened are the tendo Achillis and those of the tibials and flexor digitorum longus. 

 The tendo Achillis is displaced medially. Ligaments. — Those on the lateral side are stretched, 

 those on the medial, especially the anterior part of the deltoid, the dorsal talo-navicular and the 

 plantar calcaneo-navicular ligaments are shortened. The plantar fascia is also shortened, 

 together with the abductor hallucis, which arises from it. 



