What are the immovable articulations between adult skull bones called?

The immovable articulations between adult skull bones are called sutures. Sutures are specialized types of fibrous joints that occur exclusively in the skull. They are formed where two or more cranial bones meet, and they interdigitate to provide stability and strength to the skull structure. Over time, these joints become increasingly fused, making them immovable in adults, which is crucial for protecting the brain and forming the shape of the head.

In contrast, other terms such as joints refer to a broader category of connections between bones, which can be movable (like the knee) or immovable (like sutures) depending on the specific type of joint. Ligaments are connective tissue structures that connect bones to other bones at joints, while cartilages serve various functions in the body, including cushioning joints and providing flexibility. However, neither ligaments nor cartilages form the specific immovable articulations seen in the skull.