Neurovasculature of the cranial fossae. The anterior cranial fossa is formed from the frontal bone, cribriform plate of ethmoid, and lesser wings of sphenoid. The optic nerves pass through optic canals in the lesser wings. The middle cranial fossa is comprised of the body and greater wings of sphenoid, the squamous portion of the temporal bone, and the anterior surface of the petrous portion of temporal. The mandibular nerve passes through the foramen ovale and the middle meningeal artery through foramen spinosum. The cavernous sinus is located along the lateral surface of the body of the sphenoid and surrounds the internal carotid artery. The posterior fossa is formed from the posterior surface of the petrous bone and the occipital bone. Here, the internal acoustic meatus conveys cranial nerves CNVII and VIII, while the jugular foramen conveys CNs IX, X, and XI. CN XII passes through the hypoglossal canal. The foramen magnum, the largest of the cranial foramina, transmits the spinal cord, meninges, the vertebral arteries, and CN XI. (Image courtesy of AL Rhoton, Jr.)