What type of joints are characterized by immovable interlocking margins, typically found in the skull?

The correct answer is sutures, which are specialized types of fibrous joints. They are specifically designed for the articulation of the bones in the skull. The interlocking margins of sutures provide stability and significantly strengthen the connection between the skull bones, while preventing movement. This immobility is crucial for protecting the brain and maintaining the overall integrity of the cranial structure. Sutures typically feature a serrated or zigzag edge, which enhances the lock-and-key fit of the adjoining bones.

While fibrous joints include sutures, they also encompass other types, such as syndesmoses and gomphoses, which allow for varying degrees of movement. Synovial joints, on the other hand, are characterized by a fluid-filled joint cavity and are typically movable, which is fundamentally different from the immovable nature of sutures. Cartilaginous joints involve cartilage connections and can allow for slight movement, such as those found in the vertebral column, further distinguishing them from the completely immobile sutures found in the skull.