Page:Popular Science Monthly Volume 28.djvu/407

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ISREGARDING the action of those parts not affecting the feet, the act of walking may, as I think, be thus described: The foot put forward should reach the ground when nearly flat; the toes, the organs of feeling, should be the first to reach it, not the heel, which could not be without some concussion, however slight. The heads of the metatarsal bones and the toes are then pressed firmly against the surface. The great-toe, having only two phalanges, is held down in its whole length, the flexor tendon being attached to the final phalanx close to the joint between them. The little toes touch at their tips only; their flexor tendons being also attached to the final phalanx of each, traction on them causes a rising at the joint between the two proximal phalanges as the tips of the toes are drawn backward. By this arrangement, in the one case a firm, solid base is formed from which the body can be propelled onward; in the other an additional hold on the surface, by a rudimentary action or grasping, is afforded. As the body is moved onward, the extensors of the great and of the little toes, without lifting them from the ground, where they are held by the flexors, draw the leg forward, while the anterior tibial, in assisting this movement, serves another purpose. It is attached to the crown of the arch, and in action tends to prevent any sinking there as the weight of the body comes upon that structure. This purpose is much more effectually served in another way: the muscles of the calf allow the heel with firmness and precision, but withal gently, to touch the ground, and the step is completed.

The heel is then raised, but the weight of the body is not borne, as commonly stated, by the muscles acting on the heel and by them only: the deeper muscles, the posterior tibial with the long flexors and the long peroneal, acting round the inner and outer side of the ankle respectively, all of them assist in raising the body and at the same time have a most important influence in maintaining the arch. The tibialis posticus, attached by its expanded tendon to the tarsus on the under surface beyond the astragalus, the bone on which the weight of the body rests, materially assists in supporting the arch from below. The long flexors passing beneath the arch from one abutment to the other are, in relation to it, as bowstrings to a bow, or rather, as the two tendons cross each other, they may better be compared to the tie-rods of a roof.

This arrangement of the two tendons crossing each other is very curious: that going to the great-toe is lowest in passing round the ankle, in order to be, as nearly as possible, at the extremity of the