Human Anatomy - Kotsan I. Ya. 2009

Skeleton of the Upper Limb
Carpal Bones

The wrist consists of 8 short spongy bones. Their names reflect their shapes. The carpal bones are arranged in two rows: proximal and distal. Each row contains four bones. The proximal row comprises (from the thumb side) the scaphoid bone (os scaphoideum), lunate bone (os lunatum), triquetrum bone (os triquetrum), and pisiform bone (os pisiforme); the distal row includes the trapezium (os trapezium), trapezoid bone (os trapezoideum), capitate bone (os capitatum), and hamate bone (os hamatum). The scaphoid, lunate, and triquetrum bones form an elliptical articular surface with their proximal facets to articulate with the distal end of the radius. The pisiform bone is a sesamoid bone. It is embedded within the tendon of the flexor carpi ulnaris Muscle. On the surface of each bone, there is one or more articular facets for articulation with adjacent bones. Additionally, the palmar surfaces of certain carpal bones feature tubercles for muscle and ligament attachment, namely: the tubercle of the scaphoid bone (tuberculum ossis scaphoidei), the tubercle of the trapezium (tuberculum ossis trapezii), and the hook of the hamate bone (hamulus ossis hamati). Together, the carpal bones form a bony arch, convex dorsally and concave palmarwards. Consequently, this creates the carpal sulcus (sulcus carpi) on the PALMAR ASPECT OF the hand, bounded on the radial side by the scaphoid tubercle and the trapezium tubercle, and on the ulnar side by the hook of the hamate and the pisiform bone. Tendons, vessels, and nerves lie within the carpal sulcus.

The carpal row is easily palpable through the Skin. For instance, on the dorsal aspect of the wrist with the hand flexed, one can palpate the scaphoid, the lunate, and the capitate, which is the largest of the carpal bones. The pisiform bone can be felt on the palmar surface of the wrist on the medial side (when the hand is partially flexed at the radiocarpal joint).