150 CLINICAL APPLIED ANATOMY. 



factor in the maintenance of the arch. Of these the important 

 are, (1) The inferior calcaneo-navicular, attached behind to the 

 front of the sustentaculum tali and in front to the under and inner 

 surface of the tubercle of the navicular. This ligament underlies 

 and therefore supports the head of the astragalus, the only part 

 of that bone which can in any way be termed the keystone of 

 the arch. The ligament contains much elastic tissue, and is often 

 termed the " spring" ligament. (2) The long plantar ligament, 

 attached behind to the under surface of the os calcis and in front 

 to the margins of the groove on the under surface of the cuboid, 

 in front of the tuberosities, and the bases of the third, fourth and 

 fifth metatarsals. (3) The short plantar ligament, attached 

 behind to the front of the under surface of the os calcis and in 

 front to the under surface of the ridge forming the posterior 

 boundary of the groove on the inferior aspect of the cuboid. 

 (4) The anterior part of the internal lateral ligament of the ankle 

 joint. 



The third factor in maintaining the arch is formed by the 

 tendons of certain of the leg muscles. Of these the most 

 important are those of the tibial muscles. 



The tibialis posticus tendon passes in a groove behind the 

 internal malleolus, then across the inner surface of the susten- 

 taculum tali to the under and inner surface of the tubercle of the 

 navicular, superficial to the inferior calcaneo-navicular ligament. 

 The tendon also sends expansions backwards to the sustentaculum, 

 outwards to the cuboid and forwards to the bases of the second, 

 third and fourth metatarsals. It will thus be seen that this 

 muscle is a most powerful supporter of the longitudinal arch of 

 the foot, particularly from its position in reference to the spring 

 ligament, and through it to the head of the astragalus. The 

 tibialis anticus tendon lies anterior to the lower end of the 

 tibia, and crossing inwards on the dorsum of the foot runs to 

 be inserted into the inner and under surface of the internal 

 cuneiform and base of the first metatarsal. Both of these 

 tendons come out into prominent relief when a person stands 

 over on the outer edge of the foot. In addition to these two 



