pollex

Pollex is the anatomical term for the thumb, the first digit of the hand. The word derives from Latin pollex, meaning “thumb” or “pad of the finger.” In human anatomy, the pollex is distinguished by its opposable orientation, enabling a firm grip and precise handling of objects.

Anatomically, the pollex consists of the first metacarpal and usually two phalanges (proximal and distal), linked by the metacarpophalangeal and interphalangeal joints. It often bears two sesamoid bones within tendons that pass over the first metacarpophalangeal joint. The nail bed and surrounding soft tissues mirror those of other digits, though the pollex is shorter than the other fingers.

Functionally, the pollex participates in opposition with the other digits, allowing pinch and precision grip. Its carpometacarpal joint provides pivot and semicircular rotation, increasing grip strength and dexterity needed for tasks such as writing, manipulating small objects, and tool use.

Variation and abnormalities include polydactyly (an extra thumb) and triphalangeal pollex, where the thumb has three phalanges. Fractures of the pollex, especially involving the base of the first metacarpal (Bennett fracture) or injuries to the interphalangeal joints, are clinically significant and may require reduction or immobilization.

Evolutionarily, the opposable pollex is a defining feature of primates, with humans showing a highly dexterous thumb that supports a precision grip and tool use. The term pollex remains the standard anatomical term for the thumb in medical and biological literature.