The term “phalanges” refers to the bones that make up the fingers and toes, derived from ancient Greek. This word, which is the plural form, describes the rows of bones in the digits, much like the organized ranks of a Greek military formation known as a phalanx. The single bone unit is called a phalanx. These bones are classified as long bones due to their elongated shape, even though they are relatively small. Their primary function is to provide structure for grasping, manipulating objects, and contributing to balance and locomotion.
The Direct Answer: What Phalanges Are
Phalanges are the digital bones found in the hands and feet of most vertebrates, including humans. They are the bones that extend out from the metacarpals in the hand and the metatarsals in the foot. The term establishes a precise anatomical category for all the bones within these extremities.
The original Greek term, phalanx, referred to a block of infantry soldiers or a military battle array. Anatomists borrowed this term because the bones of the digits, arranged in parallel rows, visually resembled this organized military formation.
In total, the human body contains 56 phalanges, with 14 bones located in each hand and 14 in each foot. These bones are categorized into three types based on their position within the digit: proximal, intermediate, and distal.
Structure and Arrangement in the Hand
The human hand contains 14 phalanges, distributed across the five digits. Each of the four fingers (index, middle, ring, and little finger) is composed of three phalanges: proximal, intermediate, and distal. These are arranged sequentially from the palm to the fingertip.
The proximal phalanx is the largest and connects to the metacarpal bones of the hand. The intermediate phalanx sits in the middle, positioned between the proximal and distal bones. The distal phalanx is the smallest bone, forming the fingertip and providing structure for the fingernail.
The thumb (pollux) is the single exception to this arrangement, containing only two phalanges: proximal and distal. It lacks the intermediate bone. This two-bone structure gives the thumb its unique range of motion, necessary for gripping and opposable movement.
The joints between these bones are called interphalangeal joints, which allow for the bending and straightening of the fingers. The joint connecting the proximal phalanx to the metacarpal is known as the metacarpophalangeal joint, commonly referred to as the knuckle.
Phalanges in the Feet
The term phalanges is not exclusive to the hand, as the toes also contain these digital bones. Like the hand, each human foot is composed of 14 phalanges.
The four smaller toes each contain three phalanges: proximal, intermediate, and distal. The big toe, anatomically known as the hallux, follows the same pattern as the thumb, possessing only two phalanges. This means the big toe only has a proximal and a distal bone, missing the intermediate phalanx.
While the number and arrangement are the same, the phalanges of the foot are shorter and more robust than those in the hand. This structural difference reflects their function, as foot phalanges are primarily involved in providing stable support, balance, and propulsion during walking. The bones in the toes are often more compressed to manage the weight and forces placed on the foot.