Cranial Nerves Flashcards
CN1
Olfactory
CN2
Optic
CN3
Occulomotor
CN4
Trochlear
CN5
Trigeminal
CN6
Abducens
CN7
Facial
CN8
Vestibulocochlear
CN9
Glossopharyngeal
CN10
Vagus
CN11
Accessory
CN12
Hypoglossal
CN1: Origin & path
Origin: R & L olfactory bulbs
Path: exits skull via cribiform plate
Termination: roof of the nose
CN2: Origin & path
Origin: optic disc
Path: leaves orbit entering skull via optic canal. Runs posterior-medically towards optic chiasm. Decussation of fibres from temporal visual fields of both eyes. Terminates in lateral geniculate nucleus (in thalamus) where information is relayed to visual cortex
CN3: Origin & path
Origin: third nerve nucleus at level of superior colliculus in the midbrain
Path: emerges from ant aspect of midbrain, passing inf to posterior cerebral artery and sup to superior cerebellar artery. Pierced dura mater and enters lateral aspect of cavernous sinus. Leaves cavity via superior orbital fissure. Divides into superior and inferior branches
CN4: Origin & path
Origin: trochlear nucleus
Path: emerges from posterior aspect of midbrain. Runs anterior and inferior within subarachnoid space. Pierces dura mater adjacent to posterior clinoid process. Runs along lateral wall of cavernous sinus. Enters orbit via superior orbital fissure.
CN5: Origin
Origin: 3 sensory nuclei (mesencephalic, principle sensory, spinal nuclei of trigeminal), 1 motor nucleus (motor nuclei of trigeminal).
CN5: path
Path: at level of pons, sensory nuclei merge to form sensory root. In the middle cranial fossa the sensory root expands into the trigeminal ganglion, lateral to cavernous sinus. Gives rise to 3 divisions: ophthalmic (V1), maxillary (V2), mandibular (V3).
CN5: Path of branches
V1: travels lateral to cavernous sinus exiting cranium via superior orbital fissure
V2: travels lateral to CS exiting via foramen rotundum
V3: exits via foramen ovale