Digit (anatomy)

Adigit is a finger or toe in tetrapods. Humans have five digits on each hand and foot, which are commonly referred to as fingers and toes, respectively. The digits are numbered from one to five, starting with the thumb (or big toe) as digit one.

Structure

Each digit is composed of small bones called phalanges. The thumb and big toe have two phalanges, while the other digits have three. The phalanges are connected by joints and are covered by skin, muscles, and nails.

Function

Digits play a crucial role in grasping, manipulating objects, and locomotion. In humans, the opposable thumb allows for a powerful grip and precise movements, which are essential for tool use and fine motor skills. In other animals, digits may be adapted for various functions such as climbing, swimming, or digging.

Evolution

The evolution of digits is a significant event in the history of vertebrates. Early tetrapods had more than five digits, but the number was reduced to five in most modern species. This reduction is thought to be an adaptation to more efficient movement and manipulation.

Clinical Significance

Digits can be affected by various medical conditions, including fractures, arthritis, and congenital anomalies such as polydactyly (extra digits) and syndactyly (fused digits). Proper function of the digits is essential for daily activities, and injuries or deformities can significantly impact a person's quality of life.

See Also

• Finger
• Toe
• Phalanx bone
• Opposable thumb
• Polydactyly
• Syndactyly