Wherever two or more bones join is classified as a joint. Joints are located in all parts of the body from the skull to toes. Depending on how bones are joined, different amounts and types of movements are possible. There are three major types of joints in the body, classified by the amount of movement they allow.
Immovable Joints, or Synarthoses
Synarthroses are joints with essentially no movement. When bones are interlocked or joined together without any gap between their surfaces, they cannot move relative to each other to any substantial degree. This situation allows for synarthitic joints to flex under extreme stresses but act essentially as single bones in their ability to support and protect the body. Typical examples of these joints are the bones of the skull and pelvic girdle.
Slightly Movable Joints, or Amphiarthroses
Amphiarthroses are slightly movable joints such as are found between the ribs and sternum or between vertebrae and ribs. These joints allow slightly more movement but still provide substantial stability and protection for more delicate parts of the body.
Freely Moving Joints, or Diarthroses
Most joints of the body are diarthritic and allow free movement in one or more directions. These joints are what would normally be thought of when thinking of joints with common examples being the jaw, elbow, fingers, hips, ankles and toes. Diarthrosis joints are further subdivided according to how they articulate or how the individual bones are joined.
References
- "Gray's Anatomy: The Anatomical Basis of Clinical Practice," Susan Standring (Editor), 2008
- "Trail guide to the body: how to locate muscles, bones and more," Andrew Biel, 2005.
Member Comments