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 have individual names. They are named for the digit they represent and their relative location from the center of the body (proximal or distal).
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.
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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.