The human foot and the human hand

by George Murray Humphry

21.

I will briefly draw your attention to one other point in the anatomy of the foot; and that is, the mode in which the “metatarsal” bones are jointed with the “tarsal.” If you take hold of the ends of the metatarsal bones—in other words the “balls”—of the great toe and of the two toes next to it, in your own foot, you will find that you can move them scarcely at all; they are firmly set upon the rest of the foot, almost as though they formed one piece with it. If you then try the end of the metatarsal bone of the fourth toe you will be able to move it a little upwards and downwards; and in the case of the little toe the movement is still more distinct. This difference depends upon the mode of construction of the joints of the metatarsal bones with the tarsal, which is easily understood by the aid of the accompanying drawings, representing sections, from above downwards, through these joints. In 21, 22, and 23, which are the tarso-metatarsal joints of the great toe and the two next it, the opposed surfaces of the bones between c, c, are quite flat, so that the only movement that can take place is a slight sliding of one bone upon the other, just enough to assist in breaking the jar, but not enough to interfere with the firm basis of support which these toes are required to afford to the plantar arch in consequence of the great stress of the weight in walking being borne upon this side of the foot. In No. 24, which is the joint of the ring toe, and still more in No. 25, which is the joint of the little toe, the end of the metatarsal bone (A) is rounded and is received into a corresponding concavity or cup in the tarsal bone (B). This allows a slight revolving of one bone upon the other to take place, and permits the movement which you discover when you grasp the balls of these two toes between your fingers. The outer part of the foot needs not to be so strong and firm as the inner part, because it does not lie so nearly in the plane of gravity during walking; and the provision just described, which permits some movement in the outer two metatarsals, enables the balls of the toes to adapt themselves to inequalities on the ground, and to share more equally, under various circumstances, the weight which is thrown upon them.

Standing and Stooping.

Figs. [26].
Standing.

27.
Bowing.

28.
Stooping.