The hand moves in various and complicated ways and there is a complex array of articulations that allow flexibility of movement. The joints of the hand and wrist include hinge, gliding, condyloid and saddle joints. A hinge joint allows movement back and forth. In a gliding joint, the two surfaces of the bones are nearly flat. In a condyloid joint, an ovoid surface is received into an elliptical cavity. In a saddle joint, the opposing bone surfaces are concave-convex.
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The joints of the fingers (interphalangeal articulations), including the thumb, are hinge joints that allow for flexion and extension only.
The knuckles of the hand or metacarpal-phalangeal joints (MCP) are condyloid joints that allow flexion and extension as well as limited lateral deviation.
The Wrist and Palm
The internal joints of the wrist and palm (metacarpal-carpal and inter-carpal joints) are sometimes classified as gliding joints. The wrist and hand are better understood as an irregular collection of gliding, condyloid, and saddle joints allowing for the complex motions of the wrist, which includes varying combinations of flexion, extension and lateral deviation.
The joint between the carpal and metacarpal bones of the thumb (where the thumb joins the wrist) is the classic example of a saddle joint.
The Wrist and Arm
The wrist has a condyloid joint between the radius, ulna and carpal bones allowing for smooth movement in flexion, extension, and lateral deviations.