In the medical world, there are a number of terms that may describe common body parts and motions in atypical ways. These terms act to form a consistent array of terminology that may be universally understood by experts in the field; however, they may also confuse the lay person, and hand pronation is an example Generally speaking, hand pronation is the act of rotating the hand or hands in a way that forces the palms to face backward.
There are a number of anatomical terms that describe motion in the human body. Terms such as flexion and extension refer to the bending and unbending of the limbs or joints. Other terms like adduction and abduction allude to the movement toward and away from the body, respectively. A third set of counteracting terms that describe movement are elevation and depression. As may be suspected, elevation is the raising of a body part, whereas depression is the lowering, which may be exemplified best through the movement of an eyebrow.
These terms are wonderful tools in universally describing movement; however, in circumstances that require more complex descriptions, they tend to fall short. The feet and hands are examples of body parts that may move in complicated ways. Rather than having to use three or four basic terms in succession to describe such a movement, more specific words have been created for these appendages. There are three sets of words meaning opposite things that fill this void, among them being pronation and supination.
The hand can provide a good example. Hand pronation is the rotation of the hand, wrist, forearm, and all related structures in a direction that leaves the palm facing a more posterior, or back, position than its original orientation. Hand supination is the exact reverse motion, which is characterized by an internal rotation that leaves the palm more aligned to the front of the body than previously positioned.
Hand pronation and supination are necessary for performing a number of tasks. The complex nature of hand movement allows humans and other species to use their hands in a number of ways beneficial to survival. Handling food, cleaning one's self, and physically interacting with others would all be less possible without hand pronation and its counteraction, supination. It is therefore easy to see how a motion that is taken for granted is not only difficult to describe but also important to executing everyday tasks.