Human brainstem anterior view description 2

John A Beal, PhD

Human brainstem - anterior view - cerebral nerves

II. N. opticus - The Optic nerves (II) are large & join at the midline to form the optic chiasm, then continue laterally as the optic tracts. The optic nerve is not a true nerve but rather a CNS tract.

III. N. oculomotorius - The Oculomotor nerves (III) emerge from a depression in the midbrain, the interpeduncular fossa, just caudal to the optic chiasm.

IV. N. trochlearis - The Trochlear nerves (IV) are small & are seen on the lateral surface of the midbrain. They are the only nerves which exit from the posterior side of the brain.

V. N. trigeminus - The Trigeminal nerves (V) are large and emanate from the lateral surface of the pons.

VI. N. abducens - The Abducens nerves (VI) exit near the midline from the inferior pontine sulcus which separates the pons from the medulla.

VII. N. facialis - Moving laterally in the inferior pontine sulcus, the Facial nerves (VII) can be seen.

VIII. N. vestibulocochlearis - Slightly lateral to the facial nerve is the Vestibulocochlear nerve (VIII).

IX. N. glossopharyngeus - The postolivary sulcus is a groove running rostrocaudally on the lateral surface of the medulla. From this sulcus pass the small Glossopharyngeal nerves (IX) rostrally and...

X. N. vagus - ...the much larger Vagus nerves (X) caudally.

XI. N. accessorius - The Spinal Accessory nerves (XI) exit the cervical cord then pass rostrally through the foramen magnum to exit the cranial vault with the lossopharyngeal and vagus nerves.

XII. N. hypoglossus - The Hypoglossal nerves (XII) exit the medulla via the preolivary sulcus.