Which of the following is not a bone of the cranium?

The mandible is not a bone of the cranium; it is classified as a bone of the facial skeleton. The cranium, which encases and protects the brain, consists of several bones, including the frontal, occipital, and sphenoid bones. The frontal bone forms the forehead and the upper part of the eye sockets. The occipital bone is located at the back and base of the skull, providing a base for the brain and a connection point for the spinal cord. The sphenoid bone, often described as the keystone of the cranial floor, contributes to the base of the skull and forms parts of the eye sockets.

In contrast, the mandible, or lower jawbone, is the largest and strongest bone of the face, responsible for holding the lower teeth in place and facilitating chewing and speaking. It is movable and articulates with the temporal bone of the skull at the temporomandibular joint, which distinguishes it from the immovable bones that primarily compose the cranial structure. Understanding the distinction between cranial and facial bones is crucial in anatomy, especially when studying the skeletal system's overall organization and function.