Brainstem TBL

Cranial nerves are all a part of what?

The peripheral nervous system

What are cranial nerves covered in?

Scwhann cells for myelin

Which cranial nerves are not covered in Schwann cells?

Cranial nerves I and II

What makes the myelin for cranial nerves I and II

Oligodendrocytes in the CNS

Where are the cell bodies for sensory cranial nerves

Ganglion outside the brainstem

Where are cell bodies for motor cranial nerves

Brainstem

Which cranial nerves come off the ventral surface

All of them except for CN IV (trochlear)

Motor functions of the cranial nerves

Muscles of eye, tongue, larynx, pharynx, facial expression, mastication, traps, and SCM

Sensory functions of the cranial nerves

Light touch, pain, proprioception, etc. from face, tongue, eye

Special sensory functions of cranial nerves

Vestibular, vision, hearing, taste, smell, visceral input

Autonomic functions of cranial nerves

Parasympathetic output (salivation, HR, BP, breathing, digestion, pupil size)

Where does CN I exit

Ventral frontal lobe

Where does CN II exit

Ventral frontal lobe

Where does CN III exit

Interpeduncular fossa of the midbrain

Where does CN IV exit

Dorsal midbrain

Where does CN V exit

Anterolateral pons

Where does CN VI exit

Medial pontomedullary junction

Where does CN VII exit

Pontomedullary junction

Where does CN VIII exit

Lateral pontomedullary junction

Where does CN IX exit

Post olivary sulcus (medulla)

Where does CN X exit

Post olivary sulcus (medulla)

Where does CN XI exit

Cervical spinal cord

Where does CN XII exit

Pre olivary sulcus

Parasympathetic motor (efferents) for CN autonomic innervation

CN 3, 7, 9, 10

Visceral sensory (afferents) for cranial nerve autonomic innervation

CN 7, 9, 10

Where do all sensory or parasympathetic nerves synapse on

Ganglion

Cribiform plate

CN I

Optic canal

CN II

Superior orbital fissure

CN III, IV, VI, V1

Foramen rotundum

CN V2

Foramen ovale

CN V3

Internal auditory meatus

CN VII, VIII

Styloidmastoid foramen

CN VII

Jugular foramen

CN IX, X, XI

Hypoglossal canal

CN XII

Organization of cranial nerves

3 sensory columns

3 motor columns

Branchial motor column

SVE

Parasympathetic column

GVE

Somatic motor column

GSE

Special somatic sensory column

SSA

General somatic sensory column

GSA

Visceral sensory column

SVA and GVA

Motor nuclei

Edingar-Westphal nucleus (CN III)

Oculomotor nucleus (CN III)

Trochlear nucleus (CN IV)

Trigeminal motor nucleus (CN V)

Superior salivatory nucleus (CN VII)

Facial nucleus (CN VII)

Abducens nucleus (CN VI)

Inferior salivatory nucleus (CN IX)

Nucleus ambiguus (CN IX, X)

Hypoglossal nucleus (CN XII)

Dorsal motor nucleus of CN X (CN X)

Spinal accessory nucleus (CN XI)

Sensory nuclei

Trigeminal nuclei (CN V, VII, IX, X)

Mesencephalic nucleus (CN V)

Chief sensory nucleus (CN V)

Spinal trigeminal nucleus

Vestibular nuclei (CN VIII)

Dorsal and ventral cochlear nuclei (CN VIII)

Nucleus tractus solitarius (CN VIII, IX, X)

CN nuclei organization

Motor nuclei are more medial and anterior

Sensory nuclei are more dorsal and lateral

CN nuclei in the midbrain

Edingar-Westphal (3)

Oculomotor (3)

Trochlear (4)

Mesencephalic (5)

CN nuclei in the pons

Main (chief) sensory (5, 7, 9, 10)

Trigeminal motor nuclei (5)

Abducens (6)

Facial (7)

Superior salivatory nucleus (7)

Nucleus tractus solitarius (7, 9)

CN nuclei in the pontomedullary junction

Vestibular nuclei (8)

Cochlear (8)

CN nuclei in the medulla

Inferior salivatory nucleus (9)

Nucleus ambiguus (9,10)

Nucleus tractus solitarius (9, 10)

Dorsal nucleus (10)

Spinal trigeminal nucleus (5, 7, 9, 10)

Hypoglossal nucleus (12)

Oculomotor nucleus

All eye movements except LR6SO4

Edinger Westphal

Parasympathetic motor to the pupil

Trochlear

Innervates the superior oblique that moves the eye down and in

Mesencephalic

Proprioception from jaw

Main (chief) sensory

Light touch sensation from the face

Trigeminal motor nuclei

Motor to the muscles of mastication

Abducens nuclei

Innervates the lateral rectus moving the eye out laterally

Facial nucleus

Muscles of facial expression

Superior salivatory nucleus

Tears and salivation

Nucleus tractus solitarius

Taste

Vestibular nuclei

Equilibrium

Cochlear nuclei

Hearing

Inferior salivatory nucleus

Lacrimal salivation

Nucleus ambiguus

Muscles to pharynx and larynx

Nucleus tractus solitarius

Visceral afferent information

Dorsal vagal nucleus

Parasympathetic motor to the organs innervated by the vagus nerve

Spinal trigeminal nucleus

Receives pain and temperature information from the face

Hypoglossal nucleus

Motor to the intrinsics of the tongue

Olfactory lesion

Anosmia = rare since contralateral nostril compensates

Possible causes of olfactory lesions

Head trauma, bilateral common with Alzheimer’s and Parkinson’s disease, bilateral possible with very large frontal lobe lesions

Optic lesion

Field cuts

Oculomotor lesion in the nerve

Ipsilateral dilated pupil, down and out appearance, ptosis

Oculomotor lesion in the nuclei

Ipsilateral same s/sx

Trochlear lesion in the nerve

Ipsilateral diplopia, inability to move eye in down and intorsion

Trochlear lesion to the nuclei

Contralateral

Trigeminal lesion to nerve

Ipsilateral somatosensation, LMN s/sx to muscles of mastication

Trigeminal lesion to nuclei

Trigeminal motor - ipsilateral LMN

Sensory nuclei - review

Trigeminal lesion to tracts

Trigeminothalamic tract

Abducens lesion to nerve

Ipsilateral diplopia, esotropia

Abducens lesion to the nuclei

Ipsilateral same symptoms

Facial lesion to the nerve

Ipsilateral LMN s/sx muscles of facial expression, decreased tears, salivation, taste, sounds louder

Facial lesion to nuclei

Facial, superior salivatory, gustatory, sensory (chief, trigeminal)

Facial lesion to corticobulbar tract

Contralateral lower face UMN s/sx

Vestibulocochlear lesion to nerve or nuclei

Unilateral hearing loss

Vestibulocochlear CNS lesion

No hearing loss

Lesion to superior olivary nuclei

Sound localization

Glossopharyngeal lesion to nerve

Decreased taste and sensation in posterior tongue, swallowing/talking, salivation

Glossopharyngeal lesion to nuclei

Nucleus ambiguus, inferior salivatory, gustatory, sensory nuclei (chief, trigeminal)

Vague lesion to

Nucleus ambiguus - trouble speaking/swallowing

Nucleus tractus solitarius - issues with cardio system, digestive tract, taste to epiglottis, pharynx

Dorsal motor nuclei - parasympathetic control of organs impaired

Sensory nuclei (same pattern as CN V) for - pharynx, posterior meninges, small region near external auditory meatus

Spinal accessory lesion

Ipsilateral shoulder weakness, difficulty turning head away from weakness

Hypoglossal lesion to nuclei or nerve

Ipsilateral LMN in tongue

Hypoglossal lesion to corticobulbar tract

Contralateral UMN in tongue

Blink to threat

Input - CN II

Output - CN VII

Corneal blink

Input - CN II

Output - CN VII

Pupillary light reflex

Input - CN II

Output - CN III

Jaw jerk reflex

Input - CN V

Output - CN V

Sound reflex

Input - CN VIII

Output - CN VII, V

Gag reflex

Input - CN IX

Output - CN X

Swallowing reflex

Input - CN IX

Output - CN X

Vestibulocochlear reflex

Input - CN VIII

Output - CN III, IV, VI

Spinal cord

Motor nuclei more anterior and sensory nuclei more posterior