CONSTRUCTION OF THE FOOT AS A WHOLE 



255 



ligament is supported internally by blending with the deltoid ligament, and in- 

 feriorly by the tendon of the Tibialis posticus muscle, which is spread out into a 

 fan-shaped insertion, and prevents undue tension of the ligament or such an amount 

 of stretching as would permanently elongate it. 



In addition to this longitudinal arch the foot presents a transverse arch, at the 

 anterior part of the tarsus and hinder part of the metatarsus. This, however, can 

 scarcely be described as a true arch, but presents more the character of a half- 

 dome. The inner border of the central portion of the longitudinal arch is elevated 



FIG. 207. Skeleton of the foot, internal border. (Poirier and Charpy.) 



from the ground, and from this point the bones arch over to the outer border, 

 which is in contact with the ground, and, assisted by the longitudinal arch, pro- 

 duce a sort of rounded niche on the inner side of the foot, which gives the appear- 

 ance of a transverse as well as a longitudinal arch. 



The line of the foot, from the point of the heel to the toes, is not quite straight, 

 but is directed a little outward, so that the inner border is a little convex and the 

 outer border concave. This disposition of the bones becomes more marked when 

 the longitudinal arch of the foot is lost, as in the condition known under the name 

 of "flat-foot." 



MIDDLE CUNEIFORM 



FIRST METATARSAL 



FIG. 208. Skeleton of the foot, external border. (Poirier and Charpy.) 



Surface Form. On the rlorsum of the foot the individual bones are not to be distinguished 

 with the exception of the head of the astragalus, which forms a rounded projection in front of 

 the ankle-joint when the foot is forcibly extended. The whole surface forms a smooth convex 

 outline, the summit of which is the ridge formed by the head of the astragalus, the scaphoid, 

 the middle cuneiform, and the second metatarsal bones; from this it gradually inclines outward 

 and more rapidly inward. On the inner side of the foot, the internal tuberosity of the os calcis 

 and the ridge separating the inner from the posterior surface of the bone may be felt most pos- 

 teriorly. In front of this, and below the internal malleolus, may be felt the projection of the 

 sustentaculum tali. Passing forward is the well-marked tuberosity of the scaphoid bone, situ- 

 ated about an inch or an inch and a quarter in front of the internal malleolus. Further toward 

 the front, the ridge formed by the base of the first metatarsal bone can be obscurely felt, and 

 from this the shaft of the bone can be traced to the expanded head articulating with the base 



