

BONES OF FOOT 51 



The OS Calcis is the largest bone of the tarsus. It is roughly 

 cubical, with a projection posteriorly, forming the heel. The 

 upper surface has anteriorly two facets, divided by a groove 

 to correspond with the facets on the under surface of the 

 astragalus. On the outer side of the anterior facet is a rough 

 surface for muscular origins. The anterior surface has a smooth, 

 convex surface articulating with the cuboid bone. Posteriorly, 

 the tuberosity, which is confluent with the body of the bone, 

 1ms a surface divided into three parts. The upper part is 

 smooth and covered by a bursa, the middle portion is roughened 

 for the attachment of the tendo A-chillis, and the lower part 

 is rough and confluent with the inferior surface. On the inner 

 surface of the body is the sustentaculum tali, a stout projection 

 of bone supporting the astragalus. On the outer surface is the 

 peroneal spine, a small tubercle separating the tendons of 

 peroneus longus and brevis. 



The plantar surface is slightly concave from before back- 

 wards, and roughened for the attachment of muscles and 

 ligaments. Posteriorly, there are two tubercles, of which the 

 inner one is the larger. 



The Scaphoid is a flat, oval bone, compressed from before 

 backwards, the long axis being horizontal. It articulates pos^ 

 teriorly with the head of the astragalus, and anteriorly with the 

 three cuneiform bones. The inner surface of the bone projects 

 beyond the inner border of the foot, and forms a rounded 

 tubercle easily felt in the living subject. 



The Cuneiform Bones are three in number internal, middle, 

 and external. They articulate posteriorly with the scaphoid, 

 and anteriorly with the first, second, and third metatarsals. 

 They are wedge-shaped in form, with the points downwards, the 

 first being the largest, and not so pointed inferiorly as the 

 others. This arrangement helps to keep the concave plantar 

 surface presented by the bones of the foot. 



The Cuboid Bone is roughly cubical, and lying on the outer 

 side of the foot articulates posteriorly with the anterior surface 

 of the os calcis and anteriorly with the fourth and fifth meta- 

 tarsals. On its inner side it articulates with the external cunei- 

 form bone. On the plantar surface is an oblique ridge running 



