fossa
n. (pl.
fossae) a hollow or depressed area. In neuroanatomy, fossae range from relatively large areas, such as the anterior cranial fossa, middle cranial fossa, and posterior cranial fossa in the base of the cranium for the lobes of the brain, to small regions, such as the ethmoid fossa for the olfactory bulb and the hypophyseal fossa for the pituitary gland.