Pivot joint

In animal anatomy, a pivot joint (trochoid joint, rotary joint or lateral ginglymus) is a type of synovial joint whose movement axis is parallel to the long axis of the proximal bone, which typically has a convex articular surface.

When rotating the forearm, these movements are typically called pronation and supination.

In the standard anatomical position, the forearms are supinated, which means that the palms are facing forward, and the thumbs are pointing away from the body.

In contrast, a forearm in pronation would have the palm facing backward and the thumb would be closer to the body, pointing medially.

This article incorporates text in the public domain from page 285 of the 20th edition of Gray's Anatomy (1918)