Fibrous joints are connected by dense connective tissue, consisting mainly of collagen. In these joints the bones are firmly interlocked by irregular hacksaw-like edges. These are fixed joints where bones are united by a layer of white fibrous tissue of varying thickness. The joints between the bones are called sutures. Such immovable joints are also referred to as synarthrosis.
These joints are also called "fixed" or "immovable" joints, because they do not move. These joints have no joint cavity and are connected via fibrous connective tissue. The skull bones are connected by fibrous joints.
Sutures are found between bones of the skull. In fetal skulls the sutures are wide to allow slight movement during birth. They later become rigid (synarthrodial).
Syndesmoses are found between long bones of the body, such as the radius and ulna in forearm and the distal tibio-fibular joint in leg. Unlike other fibrous joints, syndesmoses are moveable (amphiarthrodial), albeit not to such degree as synovial joints.