186 ELEMENTARY ANATOMY. [LESS. 



The calcaneum (or os calcis) is the bone of the heel, and 

 forms the posterior part of the arch of the foot, of which 

 the astragalus forms the keystone. The os calcis projects 

 much downwards posteriorly, but not inwards, and is thick 

 and rounded at its hinder end (called its tuberosity), into which 

 is inserted the tendo A chillis of the muscles of the calf. The 

 calcaneum articulates with the astragalus above and with the 

 cuboides in front. 



The naviculare (or scaphoid of the foot) is much wider 

 than long. Behind, its surface is concave for the reception of 

 the head of the astragalus. In front it presents three surfaces 

 for articulation with the three cuneiform bones. Only the 

 innermost of these surfaces is convex, and that but very 

 slightly. 



Its inner margin sends down an obtuse process, called its 

 tuberosity. 



Of the three cuneiform bones, the innermost, the ento- 

 cuneiformej is the largest. Narrow above and broad below, 

 it presents an elongated articular surface, which is nearly flat, 

 for the metatarsal of the great toe. The meso-cuneiforme' 2 

 is the smallest bone of the tarsus. It does not reach so far 

 forwards as do its neighbours. It agrees with the ecto- 

 cuneiforute^ in presenting a nearly flat articular surface for the 

 metatarsal which joins it. 



The cuboides, placed on the outer side of the tarsus, articu- 

 lates with the os calcis behind, and with both the fourth and 

 fifth metatarsals in front. Its inferior surface is traversed by 

 a deep groove (for the tendon of the peroneus longus muscle), 

 behind which is a prominence for the attachment of a liga- 

 ment. 



7. The METATARSUS consists of five elongated bones, of 

 which the first or innermost is much the thickest and the 

 shortest. The metatarsals have long shafts, which, except that 

 of the first, are slender, and have enlarged bases and rounded 

 heads. 



The bases, or tarsal ends, of the four outer metatarsals 

 have quadrangular articular surfaces, which are almost flat, 

 and are as if bevelled off, so that the axis of each such 

 metatarsal is not perpendicular to its proximal articular 

 surface. Thus these metatarsals come to be directed more 

 inwardly than would otherwise be the case. 



The rounded heads of the metatarsals articulate with the 

 hinder concavities of the proximal phalanges. 



1 'EI/TO, inward. 2 From Mf"> middle. 3 'EKTO, without. 



