Phalanx bone
In anatomy, phalanx bones (plural phalanges) are those that form the toes and the fingers. In primates such as humans and monkeys, the two thumbs and two big toes have two phalanges, and the other fingers and toes have three Phalanges.They are also classified as long bones
The phalanges do not have individual names. They are named for the digit they represent and their relative location from the center of the body (proximal or distal).
- Proximal phalanges are closest to the main part of the hand or foot and articulate with the metacarpals of the hand or metatarsals of the foot.
- Middle or intermediate phalanges are between the distal and proximal. The thumb and big toe do not have middle phalanges.
- Distal phalanges are at the tips of the fingers and toes.
The term phalanx or phalanges refers to an ancient Greek army formation in which soldiers stand side by side, several rows deep, like an arrangement of fingers or toes.
Phalangeal formula
The number of phalanges in animals is often expressed as a "phalangeal formula" that indicates the numbers of phalanges in digits, beginning from the innermost (medial or proximal).
Most land mammals including humans have a 2-3-3-3-3 formula in both the hands (or paws) and feet. Primitive reptiles typically had the formula 2-3-4-4-5, and this pattern, with some modification, remained in many later reptiles and in the mammal-like reptiles. The phalangeal formula in the flippers of cetaceans (marine mammals) is 2-12-8-1.
Gallery
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Phalanges.
