Which type of joint is classified as immovable?

Synarthrotic joints are characterized as immovable joints. They are typically found in locations where stability and protection are more critical than mobility. An example of a synarthrotic joint is the sutures in the skull, where the bones are tightly bound by fibrous tissue. This immobility is crucial for functions such as protecting the brain and maintaining the integrity of the cranial structure, as movement could lead to injury.

Diarthrotic joints represent freely movable joints, allowing a wide range of motion, which is contrary to the immovable nature of synarthrotic joints. Amphiarthrotic joints allow for slight movement, such as in the case of the pubic symphysis, which does not align with the definition of immovability. The term "semi-movable" is not a standard classification in anatomical terminology, specifically replacing established types like amphiarthrotic or synarthrotic. Thus, the designation of synarthrotic accurately describes joints that are fixed in place, serving vital functions in the skeletal system.