The bones of the wrist are the trapezoid, trapezium, scaphoid, capitate, hamate, pisiform, triquetrum and lunate. These attach to the radius and ulna, which are the long bones in the arms. The wrist bones, their ligaments and other support structures allow various movements of the hands, including up-and-down and side-to-side rotation.
The bones of the wrist, also called the carpal bones, are largely named after their shapes. So the scaphoid is boat-shaped, while the lunate has a shape that resembles the crescent moon. The trapezium has four sides, while the trapezoid is shaped like a wedge. The triquetrum is pyramidal, and the capitate reminds people of the shape of a head. The hamate, like the trapezoid, is wedge-shaped but has a little hook known as the hook of hamate.
The complexity of the wrist joint makes it subject to injury and painful conditions. One of the most debilitating wrist conditions is carpal tunnel syndrome, where the carpal nerve in the wrist is pinched. The wrist bones are also subject to arthritis, a condition in which the cushioning between the bones wears away. Inflammation of the tendons, sprains and fractures are also very common problems associated with the wrists. People who work with their hands are especially at risk for these conditions.