Metakarpala

Metakarpala, or metacarpal bones, are the five long bones of the hand that lie between the distal row of carpal bones at the wrist and the proximal phalanges of the fingers. They form the palm’s central framework and contribute to hand shape, stability, and the ability to grip objects.

Each metakarpala has a proximal base, a long shaft, and a distal head. They are numbered I to V from the thumb (pollex) to the little finger. The bases articulate with the distal carpal row: the first with the trapezium, the second with the trapezoid, the third with the capitate, and the fourth and fifth with the capitate and hamate. The heads articulate with the proximal phalanges at the metacarpophalangeal joints, forming the knuckles. The metakarpals also serve as attachment sites for tendons and interosseous muscles that control finger movements.

Functionally, the metakarpala act as levers for finger flexion and extension, transmit loads from the fingers to the wrist, and contribute to grip strength and hand dexterity. They allow a range of motions, including bending and straightening of the fingers, with stability provided by ligaments and the surrounding joints.

Clinical relevance includes fractures and dislocations, which are common in the hand. Metacarpal fractures can result from direct trauma, punching injuries (such as the commonly referenced boxer's fracture of the fifth metakarpal neck), or crush injuries. Treatment varies from immobilization to surgical fixation based on the location and degree of displacement.

Developmentally, metakarpala ossify from primary centers in the shafts with secondary centers appearing at the distal ends later in development, contributing to the growth and maturation of the hand skeleton.