The major knuckles of the hand

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The knuckles are the joints of the fingers and toes, which are brought into prominence when the hand is clenched and a fist is made. The word is derived from the diminutive of a word for bone, found in German Knochen/Knöchlein. Anatomically, it is said that the knuckles consist of the metacarpophalangeal^[1] and interphalangeal joints of the finger. The knuckles at the base of the fingers may be referred to as the 1st^[1] or major knuckles while the knuckles at the midfinger are known as the 2nd^[2] and 3rd, or minor, knuckles. However, the ordinal terms are used inconsistently, and can be found referring to any of the knuckles.^[3][4]

The popping or cracking noise heard when "cracking your knuckles" is caused by synovial fluid filling the vacuum left by the joint's displacement.^[5]

[edit] See also

• Knuckle cracking
• Knuckle sandwich
• Knuckle-walking

[edit] References

This article incorporates text from the Encyclopædia Britannica, Eleventh Edition, a publication now in the public domain.

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