Orthopaedics

Phalanges – What are the Phalanges in Humans?

Based on the human anatomy, the toes on the feet and all the fingers (including those in our foot and hand both) are formed by the phalanges. The plural form of phalanx bones is called phalanges. In humans, all fingers and toes are made of three phalanx bones, except for the thumb (hand) and the big toes (feet) which are made of two phalanx bones. The term “phalanx or phalanges” is taken from a Greek concept of army formation. In ancient times, the Greek soldiers were made to stand side by side, resembling that of the arrangement of the fingers.

Classification the Phalanx Bones

  • The phalanx bones are basically long bones, which is their characteristic sign.
  • The phalanx bones are named based on the following criteria –
    • The digit (number of bones) they represent
    • The location of the phalanx bone in relation to the others
    • The distance of the phalanx bone from the body
  • Example, if they are located between two other phalanx bones, it might be called intermediate phalange.
  • The phalanx bones are classified into the following types –
    • Distal Phalanges –

      the phalanx bones which form the tip of the toes and fingers are called the distal phalanges. These bones are placed much away from the body; hence the name “distal” is given.

    • Proximal Phalanges –

      these bones are located closest to our body (hand or foot). The proximal phalanges articulate with the metacarpals (the transverse arch formed at the end of the palm to which the finger bones are fixed) of the hands and the feet.

    • Intermediate Phalanges –

      these include the phalanx bones which are placed between the distal and the proximal phalanges. These bones are also called middle phalanges. These bones are not found in the thumbs and the big toe.

Phalangeal formula

  • The number of phalanges in our hand and foot are expressed in digits, called the Phalangeal formula.
  • The finger bones are formed by the phalanges or the Phalanx bones.
  • Each hand of a normal human being consists of 14 planages; 3 phalanges in each of the fingers except the thumbs, which is formed by 2 phalanges. This makes up the phalangeal formula of 2-3-3-3-3.
  • The phalangeal formula states the number of phalanx bones arranged in the vertebrates. The number of phalanx bones is expressed in digits.
  • Phalangeal formula of reptiles is –2-3-4-4-5. This may be a little different in a few later reptiles and mammal-like ones.
  • Phalangeal formula in primitive mammals is –2-3-3-3-3. This formula is the same in humans.
  • Phalangeal formula of a deer is – 3-3.
  • The Phalangeal formula in Cetaceans (marine mammals) is – 2-12-8-1, which is seen at their flippers.

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