Pivot joint

Recommended video: Types of synovial joints [18:19]

Synovial joints are the main type of joints found in the body.

Pivot joints are one of six types of synovial joints along with plane joints, ellipsoid joints, hinge joints, ball and socket joints and saddle joints. 

Pivot joints got their name primarily for the movement they allow – pivoting (i.e. a shaft/axis upon and about which something rotates). This is the only movement that occurs in this joint, which is why this joint is considered an uniaxial joint. In order to accommodate this type of movement, the pivot joints usually have a rounded portion of the bone (or axis) around which another bone forms a ring and moves.

A good example of a pivot joint is the atlantoaxial joint which is formed between vertebra C1, the atlas, and the dens of vertebra C2, the axis. Note that vertebra C2 is also called 'the axis' because of the pivot point it creates for the atlas and vertebra C1 forms an enclosed ring around the dens thanks to the transverse ligament of the atlas. The rotation of the atlas around the dens is the movement we make when we shake our heads left and right (like when saying 'No').