Cranial nerves . • Exit: Where does the CN exit the CNS? And through which foramen in the cranium? • Funcon: Where does the CN aach? Muscle, gland, …? • Fiber type: Motor, sensory or both • Lesions: If you know the funcon and fiber type, you know the lesion. CN I: Olfactory nerve

Exit: Cribriform plate of ethmoid bone Funcon: Olfacon (smell): the only sense that is NOT relayed by thalamus Fibers: Sensory Lesion: Can not smell

CN II: Opc Nerve

Exits: Opc canal (opc canal: opc nerve, ophthalmic artery)

Funcon: - Vision - Afferent limb of pupillary light reflex

Fibers: Sensory

Lesions: f.eks Visual field defects: - Right monocular blindness - Bitemporal hemianopsia - Le homonymous hemianopsia Pupillary light reflex pathway

LETS DRAW Pupillary light reflex Visual field

• Nasal rena looks at the temporal eye field • Temporal rena looks at the nasal eye field • Nasal rena fibers decussate in the opc chiasm DRAW WITH ME J

Visual field defect

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• Bitemporal hamianopsia

Bitemporal hemianopia Right monocular hemianopia Le homonymous hemianopia CN III: Oculomotor nerve

Exit: Superior Orbital Fissure (III, IV, V1, VI) Funcon:

- Eye movements: All except SO and LR - (SO4LR6) 3 (Superior rectus, inferior rectus, medial rectus, inferior oblique, levator palpebrae) - Efferent limb of pupillary light reflex - PSANS fibers from EW nucleus causes pupillary constricon Fibers: Motor (Parasympathec) Lesions: On an other slide.

Lesion to CN III: Oculomotor Nerve

1. Pupil looks down and out (unopposed lateral rectus (CN VI) and superior oblique (CN IV))

2. Ptosis (loss of innervaon of levator palpebrae)

3. “Blown pupil” (dilated pupil due to loss of PSANS fibers from EW nucleus of CN III)

Anisocoria

1.Can be physiological Horners syndrome. CN IV: Trochlear nerve (Pulley)

Exit: Exits the skull through Superior Orbital Fissure

Funcon: Innervates superior oblique, which moves the eye DOWN- (SO4 LR6 )3

Fibers: Motor

Lesion: Paent complains about walking stairs.

Other important: The only nerve that exits from the dorsal aspect of the brainstem

CN V: Trigeminal nerve

● Three branches • Exit • Funcon 1. V1: Ophthalmic nerve • Fiber 2. V2:Maxillary nerve 3. V3: Mandibular nerve • Lesion

V1: Ophthalmic nerve Sensaon to the upper most par of Afferent limb of corneal (blink) reflex face

V2: Maxillary nerve

Sensaon to upper part of jaw

V3: Maxillary Nerve

Afferent AND efferent limbs of jaw jerk reflex Innervates muscles of mascaon

V3: Maxillary Nerve

SENSATION from anterior 2⁄3 of tongue SENSATION from face

CN VI: Abducens nerve

Exits: Superior Orbital fissure ( III, IV, V1, VI, ophthalmic vein)

Funcon: Innervates lateral rectus- (SO4LR6) 3

Fibers: Motor

Lesions: Diplopia on lateral gaze CN VII: Facial Nerve

Exit: Internal acousc meatus → facial canal (Gives of three branches)→ stylomastoid foramen-> Parod gland (Gives off five motor branches).

Funcon: - Innervates stapedius muscle of inner ear - TASTE from anterior 2⁄3 of tongue - Innervaon to all glands, EXCEPT parod - Muscles of facial expression Fibers: - Motor - Taste, parasympathec fibers and sensory

Lesions: UMN lesion and LMN lesions

Posterior cranial fossa -> I​nternal acoustic meatus (Gives off three branches)→ facial canal→ stylomastoid foramen-> Parotid gland (Gives off five braches).

Funcon of facial nerve

Remember the branches of the facial nerve then it will be easier to remember the funcon of it as well

7 branches of facial nerve. 1. Nerve to stapedius Innervates stapedius muscle of inner ear 2. Chorda Tympani TASTE from anterior 2⁄3 of tongue, submandibular and sublingual 3. Greater petrosal nerve Lacrimal gland, nasal gland 4. Motor branches: Muscles of facial expression and Muscles of facial expression - Temporal - Zygomac - Buccal - Mandibular - Cervical

LETS DRAW AGAIN J CN VIII: Vesbulocochlear nerve

Exit: Internal acousc meatus Funcon: Hearing Fibers: Sensory Lesion: I can’t hear you.

Nerves in cerebelloponne angle: CN VII and CN VIII CN IX: Glossopharyngeal nerve

Exit: Jugular foramen (Jugularforamen=IX,X,XI) Funcon: - Afferent limb of gag reflex - Sensaon AND taste from posterior 1⁄3 of tongue - Innervaon of parod gland

Fibers: Sensory, Parasympathec

CN X: Vagus nerve CN XI: Accessory nerve

Exit: Jugular foramen

Funcon: Innervates trapezius (shrugging) and sternocleidomastoid (turns head to opposite side)

Fibers: Motor

Lesion: Inability to shrug shoulder and turn head.

CN XII: Hypoglossal nerve

Exit: Funcon: Muscles of the tongue Fibers: Motor Lesion: Tongue deviaon to ipsilateral side

“Lick your wounds”

Quesons? • Pupillary light reflex • Corneal blink reflex • Jaw jerk reflex • Gag reflex • Cough reflex Cranial nerve reflexes