Tommelfinger

Tommelfinger is the common Danish term for the first digit of the hand, the thumb. In anatomy, the thumb is distinguished by its opposability, enabling a wide range of grips and precise handling. Humans typically have two phalanges in the thumb, compared with three in the other fingers, and it is connected to the hand by the first metacarpal. The primary joints are the carpometacarpal joint (a saddle joint), the metacarpophalangeal joint, and the interphalangeal joint. Movement of the thumb is coordinated by the thenar muscles, including the abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis, with the adductor pollicis providing power in pinches.

Function and use: The thumb’s opposability and range of motion underpin most hand function, including grip, pinch, and manipulation of objects. It allows tip-to-tip and pad-to-pad precision grips, stabilizes objects during manipulation, and contributes to complex gestures and tool use.

Etymology and usage: The word tommelfinger is a compound of tommel (thumb) and finger; the term is cognate with similar Scandinavian forms in Norwegian and Swedish, reflecting common Germanic roots. The expression tommelfingerregel means “rule of thumb,” a practical guideline based on experience rather than theory.

See also: Pollex; Thenar eminence; Opposable digit.