What does it mean anatomically when a person is described as "double jointed"?

zbeckabee

Hypermobility (also called double-jointedness, hypermobility syndrome or hyperlaxity) describes joints that stretch farther than is normal. For example, some hypermobile people can bend their thumbs backwards to their wrists, bend their knee joints backwards, put their leg behind the head or other contortionist performances. It can affect a single joint or multiple joints throughout the body. http://en.wikipedia.org/wiki/Double_jointed Aug 12 09, 5:16 AM

rb6359

Double-jointedness (or hypermobility) simply means a joint can be moved through a greater range of movement than what is considered normal. http://en.wikipedia.org/wiki/Double_jointed Examples include bending your thumb back onto your wrist or bending a knee backwards. Causes include misaligned joints, abnormal ends on the bones of a joint, collagen defects and"Abnormal joint proprioception (an impaired ability to determine where in space parts of the body are, and how stretched a joint is)". Aug 12 09, 5:18 AM