Fibrous joints are formed between bones connected by fibrous connective tissue and lack a synovial cavity. Fibrous joints can be classified into three types: syndesmoses, sutures and gomphoses. Syndesmoses are slightly movable joints connected by ligaments or interosseous membranes. Their movement depends on the length of the ligament— the longer the ligament, the more the movement. For example, the joint between the tibia and fibula and the joint between the radius and ulna are syndesmoses. Sutures are immovable joints where bones are connected by short connective tissue fibers. These interlocked joints are present only in the skull. Gomphoses are immovable peg and socket joints that exist only between the teeth and their bony sockets. The periodontal ligaments fix the roots of the teeth into the dental sockets of the maxilla and mandible.