Finger

Structure and characteristics

Each finger consists of bones called phalanges and is connected to a metacarpal in the palm. The four long fingers usually have three phalanges (proximal, middle and distal); the thumb has two. Major joints include the metacarpophalangeal joint (at the knuckle) and the interphalangeal joints. Tendons and intrinsic hand muscles control flexion and extension, while nerves (for example the median and ulnar nerves) provide sensation and motor control. The fingertip skin bears friction ridges, known as fingerprints, which enhance grip and are unique to individuals.

Names and arrangement

• Thumb (first digit)
• Index or forefinger (second digit)
• Middle finger (third digit)
• Ring finger (fourth digit)
• Little finger or pinky (fifth digit)

These names are commonly used in anatomy, daily life and legal or clinical descriptions. The thumb’s shorter length and two phalanges give it a wider range of rotation and opposition.

Evolution and development

Fingers evolved in tetrapods and were refined in primates for arboreal life and tool use. The opposable thumb, present in humans and some other primates, permits precision grips and complex manipulations that support tool making, writing and many skilled tasks. For comparative anatomy and evolutionary context see other primates.

Uses, importance and examples

Fingers serve many practical roles: they provide tactile exploration, support fine motor skills such as typing, writing, sewing and playing musical instruments, and enable complex grips for lifting and handling objects. Fingers are also central to nonverbal communication—gestures, sign languages, religious or cultural expressions—and in applying tools and technology.

Variation, health and notable facts

Fingers are subject to injuries (fractures, tendon damage), chronic conditions (arthritis), and congenital variations (polydactyly or syndactyly). Fingertip skin patterns are used in forensic identification because they are stable and individual. Cultural practices such as wearing rings frequently involve the ring finger. While many people and dictionaries include the thumb as a finger, some anatomical definitions distinguish it because of its structure and range of motion.