THE SCAPULAE ARCH. 



141 



17 



Under surface. 



to the great toe (i), and three to the other toes (11, in, IT, v) ; 

 their division is similar to that of the fingers, into base, body, and 

 head, but they are much shorter Fig. 143. 



and flatter. 



The foot of man is distin- 

 guished from the corresponding 

 part in the quadrumana by its ca- 

 pability of being planted flat upon 

 the ground, and the strength of 

 the base thus afforded ; the paral- 

 lelism and magnitude of the 

 great toe, the advanced position 

 of the astragalus, the backward 

 extension of the heel, the fixed 

 condition of the tarsus, the 

 strength of the metatarsal bones and those of the phalanges, 

 form the distinctive differences between the foot of man and 

 that of monkeys : when we notice an ourang or chimpanse 

 attempting to walk erect, the foot is seen resting on its outer 

 side, the heel scarcely projecting, and they can only sustain 

 the erect position by supporting their hands upon some body. 



[ 268*. The internal side of the foot is constructed as an arch, 

 for lodging and protecting the blood vessels, nerves, and tendons 

 of the toes ; this arch likewise forms a spring by which sudden 

 shocks are diminished, the elasticity of the tarsal and meta- 

 tarsal articulations contributing to this end ; the jar being 

 broken thereby before it is transmitted to the limb. This pro- 

 vision is still further developed in the feet of certain animals, 

 like the cats, which bound after their prey ; in addition to 

 the elasticity of the tarsus and metatarsus, their feet are sup- 

 plied with elastic pads, to break the shocks occasioned by their 

 springing habits. 



[ 269. THE SCAPULAE, like the pelvic arch, consists of three 

 pan* of bones, the scapula, the coracoid and the clavicle, 

 which are the homologues of the ilium, the ischium, and the 

 pubis ; early in life, in man, the coracoid becomes soldered to 

 the scapula, and is described as a process of the latter bone, 

 but it exists as a distinct element of the scapular arch in rep- 

 and birds, and in the ornythorhyncus among the mono- 

 trematous mammalia. 



Fig. 144 shews the right half of the scapular arch of man in 



