Hand

The hand is the terminal part of the forearm (upper hand), consisting of the palm, fingers and thumb. Humans have five fingers, one of which is the thumb and is opposable, enabling the grasping and precise manipulation of small objects.

The hand performs two major functions: gripping and tactile sensation. The palm contains dense concentrations of sensory nerve endings, making the hand one of the most sensitive regions of the body. The hand also plays a role in communication—gesturing, greeting, and sign languages.

Structure of the bones

The hand is made up of three groups of bones: the carpal bones of the wrist near the forearm, the metacarpal bones of the palm, and the phalangeal bones of the fingers. Each finger consists of three bones, except the thumb which has two. The numerous connections between these bones give the hand great mobility.

Muscles and nerves

Many of the muscles that move the fingers are located in the forearm, with tendons extending from them through the wrist to the hand. Small muscles within the hand itself control fine movements. Three major nerves—the median, ulnar, and radial—supply the hand with sensation and motor control.

Evolutionary context

Primates (gacan-saraha) generally have hands capable of grasping tree branches. In humans, combined with bipedalism, the hands were freed from locomotion, correlating with tool use. The human thumb has greater mobility than that of other animals, allowing for the manipulation of small implements.

Health and injury

The hand is vulnerable to fractures, cuts and infections. Degenerative conditions such as arthritis affect the joints. There are also conditions arising from nerve compression, such as carpal tunnel syndrome, which causes tingling and weakness in the fingers. Treatment varies depending on the condition and may involve rest, physical therapy, and medication.