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Anatomy of Skeleton 



THE METATARSUS This can be compared with the metacarpus in the hand, 

 when its constituent bones will be seen to be weaker and less divergent. Each bone 

 presents a base, shaft, and head. Notice the obliquity of the line of the tarso-meta- 

 tarsal junction, with the prominent styloid process that projects externally on the base 

 of the fifth metatarsal. The first metatarsal, carrying the big toe, is very thick and 

 strong for supporting the greater part of the weight of the body in stepping off from 

 the foot, whereas the outer portion of the metatarsus is mainly used as a support in 

 balancing the body, and not as a weight carrier, wherefore its comparative weakness. 



THE PHALANGES. As in the hand, these 

 are two in number in the big toe and three in the 

 others, numbered first, second, and third in order 

 from behind forwards in each toe. Notice the 

 thin shafts and thick extremities, save in the great 

 toe, and also observe that there is frequently 

 modification in the direction of fusion or reduction 

 in the last phalanges of the outer toes. 



When the names and general relations to each 

 other of the bones of the foot are familiar, the 

 complete skeleton of the region should be studied 

 with a view to understanding the relations and 

 significance of the various bony points, etc., in it, 

 and after that with the object of grasping 

 the means by which the arches of the foot are 

 held in position to support the weight thrown on 

 them. 



Looking first at the dorsal surface (Fig. 138), 

 we perceive that the general contour of the tarsus 

 is markedly convex from side to side and also to a 

 slight degree from behind forwards : there are no 

 prominent bony points that make themselves 

 evident above the general level. On this surface, 

 however, there are several things to be observed. 

 We can see that the astragalus consists of a stout 

 body that carries the articular surfaces of the leg 

 bones, and this is joined by a short neck with the 

 rounded head. Under the outer side of the neck 

 is the outer end of a short interosseous canal or 

 tunnel, the sinus tarsi, running obliquely forward 



and outward between the astragalus and os calcis, and lodging an interosseous ligament 

 connecting the bones : the os calcis has an exposed dorsal surface where this canal opens, 

 and here the anterior annular ligament and Extensor brevis digitorum are attached. 



The structures that pass on to the dorsum of the foot from the front of the tibia 

 stream down over the head of the astragalus and mask it somewhat when the living 

 foot is examined from the dorsum. Fig. 139 is a diagram to show the relation between 

 these structures and the underlying bones : they can be made out, in spite of their 

 general smoothness, by careful examination of the living foot. 



Looking at the dorsal surface of the anterior tarsal region the shortness of the 

 middle cuneiform is very evident : this gives the bone a square outline, whereas the 



FIG. 139. To show relation of dorsal 

 structures to the bones. 



