fingers

Fingers are the five digits at the end of each hand, including the thumb. In humans, the hand has five fingers: the thumb (pollex) and four fingers (index, middle, ring, and little finger). Each finger consists of phalanges—proximal, middle, and distal bones—with the thumb having two phalanges (proximal and distal). Joints allow bending and straightening: the metacarpophalangeal joints connect the fingers to the hand, while the proximal and distal interphalangeal joints permit flexion and extension. The thumb also forms a carpometacarpal joint that enables opposition, a key feature of precision grip.

Nerves supply sensation and coordination, with digital nerves originating from the median and ulnar nerves on the palmar side and contributing dorsally via the radial nerve. Blood flow is provided by digital arteries derived from the palmar arches. Muscles include intrinsic muscles—the thenar group at the base of the thumb, the hypothenar group at the base of the little finger, and the interossei and lumbricals that refine finger movement—and extrinsic flexors and extensors located in the forearm that act across the finger joints.

Functions: fingers allow gripping, pinching, manipulating small objects, typing, and playing instruments, supported by high tactile sensitivity in the fingertips and nail structures.

Clinical notes: common injuries include finger fractures (phalanx fractures), mallet finger (injury to the extensor tendon at the distal phalanx), and jersey finger (rupture of the flexor tendon). Other conditions include trigger finger (stenosing tenosynovitis) and Dupuytren's contracture. Variations include polydactyly or syndactyly, and there are developmental and evolutionary differences across species, though all share the general plan of a thumb opposing the other fingers.