OSSEOUS SYSTEM OF MAMMALIA. 



101 



mum of development ; being, in the Horse, a small styloid bone, attached 

 to the upper part of the tibia ; and, in the ruminants, a little square bone, 

 at the lower end of the tibia, forming the outer 

 ankle. 



The foot comes next under consideration ; 

 for which the previous examination of the 

 hand will have prepared the way. Like the 

 hand it is divided into three parts a basal 

 part, termed tarsus ; an intermediate, termed 

 metatarsus ; and the phalanges of the toes 

 (digiti pedis). The tarsus, in the human foot 

 (figs. 107, 108), consists of seven bones : the 

 astragalus, d ; the os calcis, c ; the os navicu- 

 lare, e ; the os cuboides, i ; and three cuneiform 

 bones, /, g, h. These bones constitute the 

 instep, with the arched contour of which we are 

 well acquainted. The cuboid bone on the out- 

 side, and the three cuneiform bones succeeding, 

 make up the anterior row, or that on which 

 the metatarsal bones are based : the tibia and 

 fibula conjoin with the astragalus a large 

 irregular bone, having a polished, and some- 

 what depressed, articulating surface to form 



paSfarc.^TinrfrfibTa^^asTrTgaius'; the ankle-joint. Among themselves, like those 

 />oscalcis> of the carpus, the tarsal bones are all com- 



pacted together in solid array. The os calcis, or heel bone, is situ- 

 ated below and behind the astragalus : it is the largest bone of the 

 tarsus, and receives the tendo Achillis, to which reference has pre- 

 viously been made. The os naviculare interposes between the astra- 



108 



Leg of human skeleton a, femur; b, 



Figs. 107,108. Two views of the bones of the human foot:-*, tibia; b, fibula; c, os calcis; <*, astragalus; e, os naviculare; 

 /, first cuneiform bone; g,A, the two other cuneiform bones; t, os cuboides ; k, metatarsal bones; /, phalanges. 



galus and the three cuneiform bones ; the cuboid bone rests against the 

 anterior projecting part of the os calcis. The metatarsal bones are 

 larger and stouter, in proportion to the toes, than the metacarpal are, as 

 compared with those of the fingers ; otherwise they resemble them in 



