In human anatomy, the main role of the carpal bones is to articulate with the radial and ulnar heads to form a highly mobile condyloid joint (i.e. wrist joint),[1] to provide attachments for thenar and hypothenar muscles, and to form part of the rigid carpal tunnel which allows the median nerve and tendons of the anterior forearm muscles to be transmitted to the hand and fingers.

On the palmar side, the carpus is concave and forms the carpal tunnel, which is covered by the flexor retinaculum.

The wrist is more stable in flexion than in extension more because of the strength of various capsules and ligaments than the interlocking parts of the skeleton.

[5] The formation of these centers roughly follows a chronological spiral pattern starting in the capitate and hamate during the first year of life.

[10] During radial abduction the scaphoid is tilted towards the palmar side which allows the trapezium and trapezoid to approach the radius.

[11] Both radial abduction and ulnar adduction occurs around a dorsopalmar axis running through the head of the capitate bone.

While flexion and extension consist of movements around a pair of transverse axes — passing through the lunate bone for the proximal row and through the capitate bone for the distal row — palmar flexion occurs mainly in the radiocarpal joint and dorsiflexion in the midcarpal joint.

[12] The structure of the carpus varies widely between different groups of tetrapods, even among those that retain the full set of five digits.

The remaining bones are simply numbered, as the first to fourth centralia (singular: centrale), and the first to fifth distal carpals.

However, the vast majority of later vertebrates, including modern amphibians, have undergone varying degrees of loss and fusion of these primitive bones, resulting in a smaller number of carpals.

Because many tetrapods have fewer than five digits on the forelimb, even greater degrees of fusion are common, and a huge array of different possible combinations are found.

(See Decapod anatomy) The Latin word "carpus" is derived from Greek καρπὁς meaning "wrist".