The space within the cranium is the cranial cavity whose floor is divided into the anterior, middle and posterior cranial fossa, a high to low three-tiered structure. The cranial fossa is made up of several bones that contribute to the skull base and contain several foramina through which structures enter and exit. This is summarised as follows:

Cranial fossa	Contributing bones	Foramina	Contents
Anterior (highest)	frontal, ethmoid, sphenoid (lesser wings)	foramina of cribiform plate	frontal lobe, olfactory bulb
Middle	sphenoid (body, greater wings), temporal	superior orbital fissure, foramen rotundum, foramen ovale, foramen spinosum, foramen lacerum, carotid canal	pituitary gland, temporal lobes
Posterior (lowest)	sphenoid, temporal, occipital	internal auditory meatus, jugular foramen, hypoglossal foramen, foramen magnum	brainstem, cerebellum