Tendons

• Tendons, soft tissue made up primarily of collagen, attach muscles to bones. When the muscles contract the tendons allow the muscle movement to move the bone to which they are attached. Ligaments are similar to tendons. They differ in that ligaments attach bone to bone, and so are usually the tissue that hold joints together.
  
  

Joints

• Joints are points where two bones come together. They are also sometimes called articulations. There are three primary types of joint: immovable, slightly movable and freely movable. Of these, only one subset of freely movable joints sometimes involves tendons. This subset is called pivot joints.
  
  

Pivot Joints

• Pivot joints are made up of one bone with a rounded or conical surface. This bone fits into a ring of bone or tendon to make the joint. A pivot joint allows rotation to occur, rather than the bending that is allowed by most joints. Pivot joints are also called rotary or trochoid joints.
  
  

Locations

• Pivot joints can be found where rotation rather than bending is required. The joint between the first and second vertebrae at the base of the skull is a pivot joint to allow for the head to turn from side to side. Pivot joints between the forearm and the upper arm allow the forearm to twist.
  
  

Tendons, Ligaments and Connective Tissues

• Joints are not held together with tendons. Pivot joints use tendons, but are not held together by them. Joints are held together by ligaments. Immovable joints are held tightly by a thin layer of fibrous connective tissue so that they do not allow for movement at all. The sutures in the skull are immovable joints. Slightly movable joints, such as the point where the ribs attach to the spine, are held together by fibro cartilage, allowing for little movement. Ligaments keep bones in movable joints together.