Sutures between skull bones illustrate which category of joints?

• A. Fibrous joints
• B. Cartilaginous joints
• C. Synovial joints
• D. Bony joints

Answer: (A)

Fibrous joints are joined by dense connective tissue and have no joint cavity, making them immovable or only very slightly movable. Sutures between skull bones fit this pattern perfectly: the bones are held together by dense connective tissue, there’s no cartilage or fluid-filled cavity, and the sutures act as rigid, fixed connections that keep the skull bones in place. In infants, sutures are wider to allow growth of the skull, with fontanelles present; as you age, these sutures gradually ossify into synostoses but remain within the fibrous joint category.

Cartilaginous joints involve cartilage connecting the bones and usually allow little movement but have a cartilage bridge. Synovial joints have a joint cavity with synovial fluid and are highly movable. Bony joints form when bones fuse completely.