The hand is not a single joint type, but rather a complex structure comprised of various types of joints. Predominantly, the joints within the hand are plane synovial joints, particularly between the carpal bones.
Here's a breakdown of the different joint types found in the hand:
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Intercarpal Joints: These are the joints between the carpal bones (the wrist bones). Most of these are plane synovial joints, also known as gliding joints. These joints allow for gliding or sliding movements. The arrangement of the carpal bones is often considered as two rows functioning somewhat like single synovial joints.
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Carpometacarpal (CMC) Joints: These joints connect the carpal bones to the metacarpal bones (the bones of the palm). The CMC joint of the thumb is a saddle joint, which allows for a wide range of motion, including flexion, extension, abduction, adduction, and opposition. The CMC joints of the other fingers are primarily plane synovial joints allowing limited gliding motions.
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Metacarpophalangeal (MCP) Joints: These joints connect the metacarpal bones to the proximal phalanges (the first bones of the fingers). These are condyloid joints (or ellipsoidal joints), which allow for flexion, extension, abduction, adduction, and circumduction.
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Interphalangeal (IP) Joints: These are the joints between the phalanges (the bones of the fingers and thumb). These are hinge joints, allowing for flexion and extension only. There are proximal interphalangeal (PIP) joints and distal interphalangeal (DIP) joints in each finger (except the thumb, which only has one IP joint).
In summary, the hand utilizes a combination of plane, saddle, condyloid, and hinge joints to achieve its dexterity and range of motion. The plane synovial joints between the carpal bones are especially important for the overall function of the wrist and hand.
