what are the two parts of the skull
Skull The skull is a bony structure that forms the head in most vertebrates. It supports the structures of the face and provides a protective cavity for the brain.[1] The skull is composed of two parts: the cranium and the mandible. In the human these two parts are the neurocranium and the viscerocranium or facial skeleton that includes the mandible as its largest bone. The skull forms the anterior most portion of the skeleton and is a product of cephalisationâ€”housing the brain, and several sensory structures such as the eyes, ears, nose, and mouth.[2] In humans these sensory structures are part of the facial skeleton.
Optic nerve Based on this anatomy, the optic nerve may be divided in the four parts as indicated in the image at the top of this section (this view is from above as if you were looking into the orbit after the top of the skull had been removed): 1. the optic head (which is where it begins in the eyeball (globe) with fibers from the retina; 2. orbital part (which is the part within the orbit). 3. intracanicular part (which is the part within a bony canal known as the optic canal); and, 4. cranial part (the part within the cranial cavity, which ends at the optic chiasm).[2]