The phalanges (Latin: (pl.) phalanges; (sg.) phalanx) are digital bones in hands and feet.
The human thumbs and big toes have two phalanges - proximal and distal, while the other digits have three phalanges - proximal, middle, and distal.
Within the digits, the three phalanges articulate with one another, forming interphalangeal joints. The proximal phalanges also articulate with the metatarsal bones of the foot at the metatarsophalangeal joints.
The phalanges are long bones, and each phalanx consists of three parts:
The bases or proximal extremities of the phalanges in the first row present oval, concave articular surfaces, while the bases of second and third-row phalanges show a double concavity separated by a median ridge.
The body of each phalanx is concave on the palmar surface and convex on the dorsal surface, while the sides of the body have rough areas for attachment of fibrous sheaths of flexor tendons.
The heads or distal extremities of phalanges are smaller than the bases, and each ends in two condyles (knuckles).
The proximal phalanges (Latin: (pl.) phalanges proximales, (sg.) phalanx proximalis) are the digital bones that are the closest to the foot or hand.
The middle phalanges (also known as intermediate phalanges, Latin: (pl.) phalanges mediae, (sg.) phalanx media) lie between the proximal and distal phalanges.
A middle phalanx is present in each digit foot (or hand) except for the first digit - the big toe of the foot (also the thumb of the hand), which lacks a middle phalanx. Note that the middle phalanges are intermediate not only according to their location but also in their size compared to the other two rows of phalanges.
The distal phalanges (Latin: (pl.) phalanges distales, (sg.) phalanx distalis) are the digital bones at the tips of the toes of the feet (and the fingers of the hands). The head of the distal phalanx presents a rough, elevated surface - the tuberosity of the distal phalanx.