What cranial nerves come off the midbrain?

Where do they exit the skull?

CN II (optic canal)

CN III (superior orbital fissure)

CN IV (posteriorly, exits through superior orbital fissure)

Which cranial nerves come off the the pons?

Where does it exit the skull?

CN V

V1 through the superior orbital fissure

V2 through Foramen rotundum

V3 through Foramen ovale

Which cranial nerves come off the pontomedullary junction?

Where do they exit the skull?

CN 6 (superior orbital fissure)

CN 7 (internal auditory meatus then petrotympanic fissure or stylomastoid foramen),

CN 8 (internal auditory meatus)

CN 9 (Jugular foramen)

Which cranial nerves come off the medulla?

Where do they exit the skull?

CN 10/Vagus (Jugular foramen)

CN 11/accessory spinal (Jugular foramen for descending fibers, foramen magnum for ascending fibers)

CN 12/Hypoglossal (XII is most medial, exits through hypoglossal foramen)

Posteriorly between the  midbrain and pons. Deccusates  immediately after exiting.

Is disposed to damage from trauma

Action: innervates superior oblique which looks down and in, palsy looks up and out (head tilt away from bad eye)

Motor= medial

Sensory = lateral

Which cranial nerves have branchial motor nuclei? (5)

Name the nuclei and what they project to

CN V: Trigeminal motor nucleus (fibers travel on V3 through foramen ovale to anterior belly of digastric, masseter muscle, temporalis muscle, and tensor tympani)

CN VII: Facial nucleus (fibers exit through stylomastoid foramen to the muscles of facial expression, stapedius muscle, and posterior belly of digastric)

CN IX: Nucleus ambiguus to the stylopharyngeus muscle

CN X: nucleus ambiguus to the palate and laryngeal muscles

CN XI: Spinal accessory nucleus to the sternomastoid and upper trapezius muscle

Which cranial nerves have parasympathetic nuclei? (4)

Name them and the ganglion and end organs they project to.

CN III: edinger westfall nucleus to ciliary ganglion (pupillary constrictor),

CN VII: superior salivatory nuclei to the sphenopalatine ganglion (lacrimal gland) and the submandibular ganglion (sublingual and submandibular gland)

CN IX: inferior salivatory nucleus to the otic ganglion (parotid gland)

CN X: dorsal motor nucleus of CN X to the parasympathetic glanglia of viscera)

Rostral nucleus solitarious

- location

- action

- type of nuclei

- CNs that project to it

long tract in medulla

gustatory nucleus (taste): visceral sensory nuclei

CNs VII (ant 2/3 of tongue), IX (post 1/3 of tongue), X (epiglottis and pharynx)

Caudal nucleus solitarious

-location

- action

- type of nuclei

- CNs that project to it

- long tact in lower medulla

-Cardiorespiratory nucleus: visceral sensory

- CN IX (baroreceptors in carotid body) and X (baroreceptors in aortic arch)

What cranial nerves have general sensory nuclei? (4)

Name the nuclei and what sensory modality they provide

CN V: Mesencephalic (proprioception), Chief (fine touch), Spinal trigeminal (crude touch, pain and temp); sensation to face, ant 2/3 of tongue and meninges

CN VII: Spinal trigeminal nucleus, to near external auditory meatus

CN IX: Spinal trigeminal nucleus, sensation from middle ear, pharynx, posterior 1/3 of tongue

CN X: Spinal trigeminal nucleus, sensation near pharynx, meninges, external auditory meatus, and visceral sensation

Which cranial nerves have a special somatic sensory function (not visceral special sensory)? (3)

CN I/olfactory: bipolar chemoreceptors project to mitral and tufted cells. Mitral cells synapse on the anterior olfactory nucleus to send bilateral projections. Tufted cells do not synapse and continue ipsilaterally to entorhinal cortex/piriform/pariamygdaloid cortex

CN II/optic

CN VIII/vestibulocochlear

Most cranial nerve nuclei project to or receive input from one cranial nerve. 3 main exceptions are ___.

- What they do and what cranial nerves are involved

SAT (nucleus solitarious, Ambiguus, and Trigeminal)

(all are long nuclei extending into the medulla)

Solitarious is sensory: taste rostrally and cardiorespiratory caudally. CNs VII, IX and X rostrally, and IX and X caudally.

Ambiguus is throat muscles. CNs IX and X.

Trigeminal is sensation to face, sinuses, throat, and meninges. CNs V, VII, IX, and X.

Describe the pathway of CN I (olfactory)

What type of sensory is this?

Starts with CHEMORECEPTORS (mitral or tufted cells)

Special somatic sensory

- Mitral cells synapse in anterior olfactory nucleus and send bilateral projections to the olfactory cortex

- Tufted cells DO NOT synapse and project directly to the olfactory cortex 

Functional categories for CN V and their functions

General somatic sensory: Touch, pain, temp, joint position of face, mouth, general sensory to anterior 2/3 tongue, nasal sinus, meninges

Branchial motor:  anterior belly of digastric, temporalis, masseter and TENSOR TYMPANI muscle

                     Does the jaw jerk reflex!

V1: In skull through superior orbital fissure then goes through the inferior part of the cavernous sinus (just above V2)

V2: In the skull through the foramen rotundum

V3 : In skull through the foramen ovale

Mesencephalic Nucleus

-In the midbrain

-Proprioception information

-Project up to the thalamus VPM and cortex

Chief Nucleus

-Located in the lateral pons

-Fine touch, dental pressure

-Lateral lemniscus -> VPM thalamus

Spinal Trigeminal Nucleus

Lateral pons, medulla, c-spine (very long nucleus!)

Crude touch, pain, temperature

Then goes up via the trigeminothalamic (aka trigeminal lemniscus) pathway to the VPM of the thalamus.  Of note, this tract crosses in the pons

-Downward input from the motor cortex via the corticobulbar pathway synapses in the trigeminal motor nucleus

(Nucleus located in the upper to mid pons, tegmentum, ventrolaterally)

Motor root of the trigeminal nerve runs inferomedial to the trigeminal ganglion (does not synapse) along the floor of Meckles cave and then joins V3 to exit via the foramen ovale

Tensor tympani

Anterior belly of digastric

masseter, temporalis

Does jaw jerk

UMN causes weakness of inferior contralateral face

LMN lesion causes weakness of entire ipsilateral face

Branchial motor: Muscles of facial expression, STAPEDIUS (normally works to dampen sound – this is why it gets loud with a facial palsy), posterior part of digastric muscle (posterior 1/3)

Parasympathetic: Lacrimal gland, sublingual, submandibular and all other salivary glands EXCEPT FOR THE PAROTID!!! (CN IX does this)

-Cell bodies of the parasympathetics are in their respective ganglia

Visceral sensory (special): Taste from anterior 2/3 of tongue

General somatic sensory: Sensation from small region near external auditory meatus

Facial nucleus which is in the caudal pons

-Wraps anterior and medially around the CN VI nucleus (in the facial colliculi) and exits the pons 

>Thru internal auditory canal

>Through geniculate ganglion 

>Exits out stylomastoid foramen

>Thru parotid gland but DOES NOT supply it

Posterior belly of the digastric

Stapedius

Muscles of facial expression (TZBMC branches)

superior salivatory nucleus (ponto-medullary junction) and are carried by 2 small branches off of the main trunk of the facial nerve

-1 = greater petrosal nerve: Takes off at the genu of the facial to reach the sphenopalatine (pterygopalatine) ganglion: for lacrimal gland

- 2 = chorda tympani nerve: Travels with lingual nerve to reach the submandibular ganglion: for salivary glands

Sensation of outer ear

ends in spinal trigeminal nucleus

Start at taste for the anterior 2/3 of tongue

>Lingual nerve and chordae tympani nerve also carry special visceral sensory fibers for taste

>Primary sensory taste fibers have their cell bodies in the geniculate ganglion

>Go through IAC, Then synapse onto secondary neurons in the ROSTRAL nucleus solitarius (aka the gustatory nucleus)

>Ascending projections continue via central tegmental tract

> Tertiary sensory neurons in VPM of thalamus that then project to cortical taste areas  

What kind of receptor does the auditory nerve use?

Where is the cell body?

mechanoreceptor

cell body in the spiral ganglion

Superior and Medial: travel up ascending MLF to VOR in VP nucleus of thalamus 

Lateral and Inferior: travel down the lateral vestibulospinal tract for balance and body position

Medial and Inferior: travel down the medial vestibulospinal tract for head and neck positioning

Ampullae of the semicircular canals detect ANGULAR acceleration

Macula of otolith organs (utricle and saccule) detect LINEAR acceleration, head tilt and transmit info to vestibular nerves

Stylopharyngeus muscle:

that IX is more important in afferent limb and X is more common on efferent limb

Arises from the nucleus ambiguus in lateral medulla

>Travels out through jugular formaen from skull

>Then the ganglia are outside of the skull – goes thru the superior and inferior glossopharyngeal ganglion to the muscle target

Bilateral innervation

To parotid gland

 inferior salivatory nucleus in the pons

>Leave glossopharyngeal nerve via the tympanic nerve and join the LESSER petrosal nerve

>synapse in the OTIC GANGLION (located in infratemporal fossa below foramen ovale) where they provide postganglionic parasympathetics to the parotid

Starts in nucleus ambiguus in the medulla

>Goes thru jugular foramen

>Goes thru superior and inferior vagal ganglion

>Becomes pharyngeal nerve:Innervates palatoglossus, pharyngeal muscles

- 2 other options:

  -Forms superior laryngeal nerve which goes and innervates cricothyroid

 - Forms recurrent laryngeal nerve which innervates the vocal cords

CN V (supratentorial meninges, to spinal trigeminal nucleus)

CN X (infratentorial meninges, to spinal trigemnial nucleus)

-Sensation from the pharynx, larynx, meninges, ?ear

>Goes in the SUPERIOR vagal ganglion and has a cell body there.

>Thru the inferior vagal ganglion

>Jugular foramen

 >Spinal trigeminal nucleus

Taste from epiglottis, posterior pharynx

>Jugular foramen

>Cell body in inferior vagal ganglion

>ROSTRAL nucleus solitarius

 >Projects up B/L to VPM

Chemoreceptors, baroreceptors in aortic arch

>Thru jugular foramen

>Cell body in inferior jugular ganglion

>CAUDAL nucleus solitarius

 >Projects up B/L to VPM

ipsilateral shoulder weakness and weakness turning head away from lesion

sternoclinomastoid normally turns head away from the side of the  muscle

Which cranial nerves have sensory (not parasympathetic) ganglia? 

Name them

CN V: Trigeminal ganglion for face/mouth/sinus sensation

CN VII: geniculate ganglion (for anterior 2/3 tongue taste and ear sensation)

CN VIII: Spiral ganglia for hearing and Scarpa's ganglia for for vestibular sensation

CN IX: Superior (Jugular) ganglion for middle ear, pharynx, and posterior 1/3 tongue general sensation; Inferior (petrosal) for above plus taste of posterior 1/3 tongue and carotid body inputs

CN X: Superior (Jugular) ganglion for sensation to pharynx, ear, and infratentorial meninges; Inferior (nodose) ganglion for laryngeal sensation, taste from epiglottis, and aortic arch inputs