Phalanges Information
In anatomy, phalanx bones (plural phalanges) are those that form the fingers and toes. In primates such as humans and monkeys, the thumb and big toe have two phalanges, while the other fingers and toes consist of three. Phalanges are classified as long bones.
The phalanges do not really have individual names. They are named for the digit they represent, their distance from the body and, in the case of the intermediate phalange, their location relative to each other.
- Distal phalanges: are at the tips of the fingers and toes.
- Proximal phalanges: are closest to 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.
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 medial). 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. Primitive mammals, however, evolved feet with the formula 2-3-3-3-3, which remains in humans, among many phalangeal formulae such as 2-12-8-1.[1]
See also
References
- ^ Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 203–204. ISBN 0-03-910284-X.
Categories: Long bones | Vertebrate anatomy
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