THE FOOT IN MAN. 491 



inferiorly, but produced into two tuberosities on wbicb the 

 heel rests. The form and disposition of the astragalar, 

 naviciilar, and calcaneo-cuboid articulations are such that 

 the distal moiety of the tarsus is capable of only a slight 

 rotatory motion upon the proximal portion. 



The distal articular surface of the ento-cunei£orm bone 

 is very nearly flat, though it has a slight convexity from 

 side to side, and is irregulai-ly concavo-convex, from above 

 downwards. The comparatively slight mobility of the 

 metatarsal bone of the hallux arises partly from this circum- 

 stance, partly from the fact that the proximal articular 

 surfaces of the four oiiter metatarsal bones are not 

 perpendicrdar to the axes of those bones, but are ob- 

 liquely truncated, from the tibial side, backwards, to the 

 fibular side. Hence the four outer metatarsal bones, instead 

 of diverging widely from the hallux as they would do 

 if their axes were pei-pendicular to the distal facets of the 

 meso- and ento-cunei£orm and cuboid bones, take a direc- 

 tion more nearly parallel with the metatarsal of the hallux, 

 and the base of the second metatarsal, as it were, blocks the 

 latter, in adduction. The hallux thus loses most of its 

 prehensile functions ; but, in exchange, it plays an important 

 part in supporting the weight of the body, which, in the 

 erect position, falls on three parts of the pes; namely, 

 the heel, the outer edge, and the integumentary pad which 

 stretches beneath the metatarso-phalangeal articulations, 

 from the hallux to the fifth digit. 



In the infant, the sole naturally turns inwards, and the 

 digits (especially the hallux) retain much of their mobility. 



The only muscles which exist in Man, but have not yet 

 been found in any Ape, are the extensor primi internodi 

 poinds and the peronceus tertius. 



The only peculiarities in the origin of muscles which 

 ordinarily obtain in Man, and have not yet been found in 

 the Apes, are — the complete separation of the flexor pollicis 

 longus from the^ea;or digitorum perforans ; the presence of a 

 tibial, as well as of a fibular, origin of the soleus; the 

 origin of all four heads of the flsxor brevis digitorum pedis 



