daumen

Daumen, the German word for the thumb, refers to the short, opposable first digit of the hand in humans and many primates. It is defined by its ability to oppose the other fingers, a feature that enables a wide range of precise grips and fine manipulations.

Anatomy: The thumb consists of two phalanges (proximal and distal) and the first metacarpal. It articulates with the wrist at the carpometacarpal joint, which permits rotation and opposition. The nail plate covers the dorsal side. Muscles both inside the hand and in the forearm control flexion, extension, abduction, adduction, and opposition.

Function: The thumb’s opposition allows grasping and pinching, contributing substantially to grip strength and dexterity. Compared with other digits, its mobility and rotational capacity enable complex tasks, from handling small tools to performing delicate operations.

Evolution and variation: The evolution of a robust opposable thumb is a key feature of human and other primate hand development, closely linked to tool use and manual skill. Across primates, the degree of thumb mobility varies with ecological needs and behaviors.

Medical and cultural aspects: Common thumb injuries include fractures and ligament injuries such as Skier’s thumb or Gamekeeper’s thumb, which affect the ulnar collateral ligament at the metacarpophalangeal joint. Culturally, Daumen features in phrases like Daumen drücken (to keep one’s fingers crossed) and Daumen hoch (thumbs up), reflecting its symbolic role in approval and luck.

See also: Pollex.