Comparative foot morphology

Comparative foot morphology involves comparing the form of distal limb structures of a variety of terrestrial vertebrates. Understanding the role that the foot plays for each type of organism must take account of the differences in body type, foot shape, arrangement of structures, loading conditions and other variables. However, similarities also exist among the feet of many different terrestrial vertebrates. The paw of the dog, the hoof of the horse, the manus (foot) and pes (foot) of the elephant, and the foot of the human all share some common features of structure, organization and function. Their foot structures function as the load-transmission platform which is essential to balance, standing and types of locomotion (such as walking, trotting, galloping and running).

The discipline of biomimetics applies the information gained by comparing the foot morphology of a variety of terrestrial vertebrates to human-engineering problems. For instance, it may provide insights that make it possible to alter the foot's load transmission in people who wear an external orthosis because of paralysis from spinal-cord injury, or who use a prosthesis following the diabetes-related amputation of a leg. Such knowledge can be incorporated in technology that improves a person's balance when standing; enables them to walk more efficiently, and to exercise; or otherwise enhances their quality of life by improving their mobility.

Limb and foot structure of representative terrestrial vertebrates:

There is considerable variation in the scale and proportions of body and limb, as well as the nature of loading, during standing and locomotion both among and between quadrupeds and bipeds. The anterior-posterior body mass distribution varies considerably among mammalian quadrupeds, which affects limb loading. When standing, many terrestrial quadrupeds support more of their weight on their forelimbs rather than their hind limbs; however, the distribution of body mass and limb loading changes when they move. Humans have a lower-limb mass that is greater than their upper-limb mass. The hind limbs of the dog and horse have a slightly greater mass than the forelimbs, whereas the elephant has proportionally longer limbs. The elephant's forelimbs are longer than its hind limbs.

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