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Joint movement
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Body movement takes place at the synovial joints, which are the freely movable ones. They are also called diarthroses, and they are grouped by the type of movement they let you make.
The problem they solve is friction between the bones that meet there. They solve it in two ways at once: there is a cavity filled with synovial fluid between them, which lubricates, and every rubbing surface is covered by hyaline cartilage, a smooth, firm cartilage. The bones do not touch: they glide.
The shape of the joint decides how much movement is possible. A hinge joint is uniaxial, meaning it moves on a single axis, and it only flexes and extends; a door hinge opens one way. A condyloid joint adds abduction and adduction, which are moving apart and moving back together. And a ball-and-socket joint adds rotation as well: it is the ball joint of a rearview mirror, which turns in every direction.
In brief
Body movement takes place at the synovial joints, the freely movable joints or diarthroses, which are classified by the movement they allow.
Their job is to prevent friction between the bones that meet there: a cavity filled with synovial fluid separates them, and hyaline cartilage covers each articular surface.
A hinge joint is uniaxial and only flexes and extends; a condyloid joint adds abduction and adduction; a ball-and-socket joint adds rotation.
A door hinge opens one way; a rearview mirror's ball joint turns every way.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Joints, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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