39 Anatomy Applied to Medicine and Surgery. 



The Arches of the Foot, two in number, are the 

 longitudinal and the transverse. The longitudinal arch 

 reaches from the posterior part of the os calcis to the 

 heads of the metatarsal bones, while the transverse is best 

 marked along the tarso-metatarsal joints. These arches 

 protect the delicate plantar tissues and give a certain 

 amount of springiness to the gait, thus preventing sudden 

 jars, etc., to the foot, and, being composed, as they are, of a 

 number of bones bound together, they give elasticity 

 to the tread. The particular part of the foot contributing 

 to this elasticity is the portion of the arch formed by the 

 astragalus, the scaphoid and the cuneiform bones, whereas, 

 the os calcis and the cuboid afford solidity and strength, 

 and thereby 'assist in supporting the more elastic portion 

 of the foot. In a longitudinal section of the foot the os 

 calcis is seen to form one side of this arch the scaphoid, 

 cuneiform and the metatarsal forming the other, while, 

 superimposed on them,, is the astragalus forming the key- 

 stone of the arch (Fig. 10). On a transverse section 

 through the cuneiform and cuboid bones, the wedge- 

 shaped middle cuneiform forms the summit or keystone 

 of the transverse arch. These arches are supported by 

 (1) the plantar fascia holding together the ends of the 

 longitudinal arch; (2) the inferior calcaneo-scaphoid lig- 

 ament, which, attached to the sustentaculum tali behind 

 and the scaphoid in front, supports the head of the astra- 

 galus, and containing, as it does, a considerable amount of 

 elastic tissue, gives, therefore, spring and elasticity to 

 the longitudinal arch; (3) beneath this ligament, the ten- 

 don of the tibialis posticus passes forward to the scaphoid 

 bone, and, therefore, assists in supporting the head of the 

 astragalus and in maintaining the arch of the foot when 

 the weight of the body is thrown on it in walking, etc. 

 This tendon has a number of processes that pass to the 



