A leg is a weight bearing and locomotive anatomical structure , usually having a columnar shape . During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element capable of changing length and rotating about an omnidirectional " hip " joint .
As an anatomical animal structure it is used for locomotion. The distal end is often modified to distribute force (such as a foot ). Most animals have an even number of legs .
As a component of furniture it is used for the economy of materials needed to provide the support for the useful surface, the table top or chair seat .