Digit (anatomy)

A digit is one of several most distal parts of a limb, such as fingers or toes, present in many vertebrates.

Some languages have different names for hand and foot digits (English: respectively "finger" and "toe", French: "doigts" and "orteils").

In other languages, e.g. Russian, Polish, Spanish, Portuguese, Italian, Czech, Tagalog, Turkish, Bulgarian, and Persian, there are no specific one-word names for fingers and toes; these are called "digit of the hand" or "digit of the foot" instead.

Humans normally have five digits on each extremity. Each digit is formed by several bones called phalanges, surrounded by soft tissue. Human fingers normally have a nail at the distal phalanx. The phenomenon of polydactyly occurs when extra digits are present; the utility of such a mutation is case-dependent.

Each finger has an orderly somatotopic representation on the cerebral cortex in the somatosensory cortex area 3b, part of area 1 and a distributed, overlapping representation in the supplementary motor area and primary motor area.

The somatosensory cortex representation of the hand is a dynamic reflection of the fingers on the external hand: in syndactyly people have a clubhand of webbed, shortened fingers. However, not only are the fingers of their hands fused, but the cortical maps of their individual fingers also form a club hand. The fingers can be surgically divided to make a more useful hand. Surgeons did this at the Institute of Reconstructive Plastic Surgery in New York to a 32-year-old man with the initials O. G.. They touched O. G.’s fingers before and after surgery while using MRI brain scans. Before the surgery, the fingers mapped onto his brain were fused close together; afterward, the maps of his individual fingers did indeed separate and take the layout corresponding to a normal hand.

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