Supination is a position of either the forearm

Forearm

-See also:*Forearm flexors*Forearm muscles...

 or foot; in the forearm when the palm faces anteriorly, or faces up (when the arms are unbent and at the sides). Supination in the foot occurs when a person appears "bow-legged" with their weight supported primarily on the anterior of their feet.

The hand is supine in the anatomical position (i.e., palms facing up during autopsy). This action is performed by the Biceps brachii and the Supinator muscle

Supinator muscle

In human anatomy, the supinator is a broad muscle in the posterior compartment of the forearm, curved around the upper third of the radius. Its function is to supinate the forearm.-Terminology:...

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Supination is the opposite of pronation

Pronation

In anatomy, pronation is a rotational movement of the forearm at the radioulnar joint, or of the foot at the subtalar and talocalcaneonavicular joints. For the forearm, when standing in the anatomical position, pronation will move the palm of the hand from an anterior-facing position to a...

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History

Originally, supination of the forearm was attributed as a function of the brachioradialis muscle. However, the original idea of the biceps acting as a supinator was something hypothesised by Leonardo da Vinci

Leonardo da Vinci

Leonardo di ser Piero da Vinci was an Italian Renaissance polymath: painter, sculptor, architect, musician, scientist, mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist and writer whose genius, perhaps more than that of any other figure, epitomized the Renaissance...

, in a series of annotated drawings made between 1505 and 1510 (referred to as his Milanese period); in which the principle of the biceps as a supinator, as well as its role as a flexor to the elbow was devised. However, this function remained undiscovered by the medical community as da Vinci was not regarded as a teacher of anatomy, nor were his results publicly released.

It was not until 1713 that this movement was re-discovered by William Cheselden

William Cheselden

William Cheselden was an English surgeon and teacher of anatomy and surgery, who was influential in establishing surgery as a scientific medical profession.-Life:...

, and subsequently recorded for the medical community, being rewritten several times by different authors wishing to present information to different audiences. Nevertheless, the most notable recent expansion upon Cheselden's recordings was achieved by Guillaume Duchenne

Guillaume Duchenne

Guillaume-Benjamin-Amand Duchenne was a French neurologist who revived Galvani's research and greatly advanced the science of electrophysiology...

in 1867 in a journal named Physiology of Motion, something which to this day is one of the major references on supination action of the biceps brachii.

In running

In running, supination (also referred to as underpronation) is the insufficient inward roll of the foot after landing. This places extra stress on the foot and can result in iliotibial band syndrome of the knee, Achilles tendinitis, plantar fasciitis.