The Foramina of the Skull Base

Key points

• • The base of the skull has many named foramina, each transmitting particular nerves and vessels, so knowing them helps localise disease.
• • The cribriform plate lets the olfactory nerve fibres for smell pass, and the optic canal transmits the optic nerve and the ophthalmic artery.
• • The superior orbital fissure transmits the nerves that move the eye (the third, fourth and sixth) and the first division of the trigeminal nerve.
• • The foramen ovale transmits the third (mandibular) division of the trigeminal nerve, while the foramen spinosum transmits the middle meningeal artery.
• • The internal acoustic meatus transmits the facial and vestibulocochlear nerves, and the jugular foramen transmits the ninth, tenth and eleventh cranial nerves along with the internal jugular vein, which begins there from the sigmoid sinus.
• • The foramen magnum, the largest, transmits the junction of the medulla and spinal cord, the vertebral arteries with the anterior and posterior spinal arteries, and the ascending spinal roots of the accessory nerve (the eleventh nerve).