CNs IX, X, XI, XII

What clinical test can you do to assess the function of CN XII?

-*protrusion of the tongue* - especially by genioglossus

How does CN XI enter the brain? Exit?

-CN XI enters brain via *foramen magnum* -> briefly joints w CN X -> then XI and X (and also IX, separately) exit brain via *jugular foramen*

overview of where all the cranial nerve roots arise

-cranial nerves arise from the brainstem roughly in numerical sequence from rostral to caudal except for CN I and CN II which arise from the forebrain -each CN exits skull through a specific foramen -within brainstem, CNs arise from *motor* or *sensory* *nuclei*. Each nucleus can be involved in the motor or sensory functions of one or more cranial nerves. Similarly, each cranial nerve can have both sensory and motor functions, as well as connections with one or more cranial nerve nuclei -some cranial nerves have peripheral ganglia that contain either primary sensory neurons or parasympathetic postganglionic neurons

put in slide 17 as an overview of the tracts

-dorsal motor nucleus most medial -n solitarius solitary to the side of it -trigeminal is most lateral think it exits the brain laterally cuz it's so big

How would the tongue protrusion test appear if there was an injury?

-got to think that each genioglossus muscle (bilat, symmet) is working to keep the tongue centered. -If one is injured, the other will take over and push the tongue towards the injured side. Ex: Injury to left hypoglossal nerve -> tongue deviates to left because right takes over. You will also get eventual atrophy of this muscle since this is a LMN lesion!

ONTO SPECIFIC CRANIAL NERVES: STARTING W CN 10 = VAGUS Overview What part of nervous system (SNS, PNS, etc)? What does it supply?

-major PARASYMPATHETIC nerve of the body -distributes PREGANGLIONIC PARASYMPATHETIC AXONS to viscera of the neck, thorax, and most of the abdomen -exits skull via jugular foramen -> pharynx, larynx, heart, lungs, esophagus, abdomen

Which cranial nerves are pure motor? Pure sensory? Mixed?

-pure motor = 3, 4, 6, 11, 12 -pure sensory = 1, 2, 8 -mixed = 5, 7, 9, 10

What happens to vocal cords if there's a vagus nerve injury?

-vocal cords paralyze -> *dysphonia* - hoarseness of the voice

What are the 5 functional components of the vagus nerve?

1) *Parasympathetic* 2) *Skeletal Motor* 3) *Visceral Sensory* 4) General Sensory 5) Special Sensory (taste)

Types of cranial nerve motor functions

1) *somatic motor* = general somatic efferent -innervation of skeletal muscles such as extraocular muscles (CN 3, 4, 6) and intrinsic muscles of the tongue (CN 12) 2) *Branchial motor* = special visceral efferent -innervation of skeletal muscles that have a different embryological origin than those innervated by somatic motor nerves. These includes muscles of mastication (CN V), facial expression (CN VII), middle ear (CN V and VII), pharynx and larynx (CN IX, X), SCM + trap (CN XI) 3) *Parasympathetic* = general visceral efferent -motor innervation for SM or cardiac muscle. CN 3, 7, 9, 10.

Types of cranial nerve sensory functions

1) *visceral sensory* a) *taste* - CN 7, 9, *10 b) *general visceral sensory* - CN *9, 10 2) *general somatic sensory* -sensation for face, sinuses, meninges. CN 5, 7, *9, *10 3) *special sensory* -CN 1, 2, 8 (vestibular sensation/hearing),

What are the two clinical reflex tests you can do to assess the skeletal motor component of the vagus nerve?

1) gag reflex! CN X provides the MOTOR component of the gag reflex [Vegas made me gag] 2) soft palate/uvula elevation when patient says "ah"

What are two clinical tests you can do for CN XI?

1) trapezius -> shrug shoulders [injury -> drooping of shoulder, mild scapular winging] 2) SCM -> ask them to turn their head to the side [injury -> can't turn head] Cervical LN biopsies may be the most common cause of CN XI injury

Which 4 cranial nerves also have parasympathetic involvement?

3, 7, 9, and 10 -3: oculomotor - pupillary constrictor, ciliary muscle of eyeball via ciliary ganglion -7: salivary and lacrimal glands via submandibular and pterygopalatine ganglia -*9: salivary glands via otic ganglion* which hops onto branches of V3 to the parotid gland [remember parotid - think you make saliva when you make that tongue noise] -10: CV, respiratory, and GI systems

ONTO CN XI: SPINAL ACCESSORY NERVE -From where do the axons of this nerve take origin? -What two muscles does it innervate?

CN XI: SPINAL ACCESSORY -axons of this nerve take origin from *ventral horn of the upper 5 cervical spinal cord segments* [think accessories on your neck - cervical spinal cord is in your neck] -innervates *trapezius* and *Sternocleidomastoid (SCM)*

ONTO CN XII = HYPOGLOSSAL NERVE -what does it innervate? -via what nucleus?

CN XII - HYPOGLOSSAL NERVE -innervates all *intrinsic muscles of tongue*, most *extrinsic muscles* eg: *genioglossus muscle* -*hypoglossal nnucleus* - very medial

When there's a vagus nerve lesion, what happens on the injured side? To what side does the uvula deviate?

Damage to CN X -> a) palate fails to elevate on injured side, b) uvula deviates to contralateral side [think it's getting picked up by the good side]

Glossopharyngeal nerve - skeletal motor component -supplies what muscle? -which nucleus?

Glossopharyngeal nerve - skeletal motor component -supplies *stylopharyngeus muscle* - helps elevate pharynx during swallowing [think of the name of the nerve!!] ( -> then swallowing takes over aka vagus) -via *nucleus ambiguus* [ambiguous interpretive dance w skeletal muscle mvmnt]

Onto Visceral sensory component of glossopharyngeal nerve: -via what nucleus? -what information?

Glossopharyngeal nerve - visceral sensory component: -via *nucleus solitarius* [again, gotta be alone for my visceral urges] -sensory from: a) *carotid body* - chemoreceptor b) *carotid sinus* - pressure receptor [think alphabet when distinguishing a from b] ^^These two influence reflex control of bp and heart rate [Think for this nerve in the video your fingers are close to your carotids!]

ONTO CN 9 - GLOSSOPHARYNGEAL NERVE Overview - what's its major function - motor or sensory?

Glossopharyngeal nerve: -primary function is *sensory* - general somatic, visceral, and special. But it also does have motor components. Less imp background: -CN IX takes origin from medulla and passes out of skull via jugular foramen. -CN IX has two sensory ganglia (superior and inferior) situated near the jugular foramen of the skull through which the nerve exits the skull

Starting with the general sensory component of the glossopharyngeal nerve: -Via what nucleus? -What sensations? -Responsible for what reflex? What arm of the reflex?

Glossopharyngeal nerve: general sensory - carries sensory from: -middle ear cavity and Eustachian tube (pain). So you can get pain from otitis media here! [Think sometimes I make that tongue sound because I have an itch in my middle ear] -posterior 1/3 of tongue (pain and touch) -soft palate (pain and touch) [lift the soft palate to make the noise] -pharynx (pain and touch) ^^^These fibers constitute the SENSORY component of the *gag reflex* [think of 9 and 10 tag teaming for the gag reflex. 9 sensory, 10 motor] [think you're TOUCHING these areas in the video hence sensory] -all communicates through the *spinal trigeminal nucleus and tract* [remember that's where all the GENERAL sensory stuff happens - video]

What is lateral medullary syndrome/Wallenberg syndrome? What is it caused by? What are the manifestations?

Lateral Medullary Syndrome/Wallenberg Syndrome [Saw T Pain LATEral/WELLenberg into my college career] - v imp! -stroke of the vertebral/PICA (posterior inferior cerebellar artery) [I get so excited about T Pain I get PICA] -> knocks out upper lateral quadrant of medulla when infarcted -> several manifestations: a) dizziness, vertigo, nystagmus, vomiting, diplopia - because vestibular nuclei have been knocked out [I was dizzy with excitement to see him] b) hoarseness, difficulty swallowing - because nucleus ambiguus knocked out [screamed so much I was hoarse] b) loss of pain and temp IPSILATERALLY in the face - because trigeminal nerve is out [saw T pain about 5 years ago -> CN 5] c) loss of pain and temp CONTRALATERALLY in the body - because STT is out [STT - T pain] Less imp: d) ipsilateral cerebellar signs, ataxia - because inferior cerebellar peduncles are out e) ipsilateral Horner's syndrome - because sympathetics are out

What is medial medullary syndrome? What's it caused by? What

Medial medullary syndrome -caused by infarct in *anterior spinal, vertebral territory artery* -this spares what was in Wallenborg syndrome -deviation of the tongue, tongue atrophy, speech problems -> bc hypoglossal nerve is out [remember 12 was the ballsy one who went medial] -contralateral hemiplegia in the body - bc medial corticospinal tract is out -loss of contralateral discriminative touch in the body - bc DCML is out

Onto parasympathetic component of glossopharyngeal nerve: -via what nucleus? -what structure is innervated?

Parasympathetic component of glossopharyngeal nerve: -via *inferior salivatory nucleus* -> otic ganglion -> *parotid salivary gland* -this is motor innervation [think: when you make that tongue noise from the video you are making some saliva!]

Special Sensory Component of Glossopharyngeal Nerve -which sense? -from where does it derive sensation? -via which nucleus?

Special Sensory Component of Glossopharyngeal nerve -*taste* on *posterior 1/3 of tongue* -via *nucleus solitarius* aka *gustatory nucleus*

Starting with the parasympathetic function of CN X -from what nucleus do these fibers arise? Are they motor or sensory? What are their functions?

Vagus Nerve: Parasympathetic Function -*dorsal motor nucleus* (and nucleus ambiguus according to outline) [gotta close the DOR and get away from all these ppl in vegas so I can rest and digest] -> preganglionic parasympathetic fibers to *viscera of neck, thorax, and abdomen* -Functions: decrease heart rate, glandular secretion, increase digestive functions

Onto vagus nerve general/somatic sensory: -what region does it innervate? -where does the information pass through?

Vagus nerve general sensory component: -innervates *external auditory meatus* - small area of skin of external ear canal [Think the music was so loud in Vegas I can't even hear anything! Just external - nothing crazy!] -information passes through the *spinal nucleus of the trigeminal nerve* [think the trigeminal does all that sensory stuff from the video in general]

Vagus nerve skeletal motor component -via what nucleus? -what are the functions? -What are some important branches?

Vagus nerve skeletal motor component: -via *nucleus ambiguus* [doing my AMBIGUUS interpretive dance with crazy skeletal muscle movements] -*swallowing - muscles of pharynx, soft palate, uvula, larynx* [injury -> *dysphagia* = difficulty swallowing.] -Some important branches = *laryngeal nerves*, such as the *recurrent laryngeal nerve* - important for speaking! [In Vegas you gotta get moving. Gotta talk the talk! You gotta take big risks, take a big gulp and go for it.]

Vagus nerve special sensory function: -what sense? -how does it travel?

Vagus nerve special sensory function: -*taste* fibers from epiglottis and pharynx [Think you could always use a taste of Vegas!] -pass to the *nucleus solitarius* [but I wanna be alone to taste it because I'm self conscious/want all the food to myself]

Vagus nerve visceral sensory component -via what nucleus? -where does it convey information from? -what two reflexes is it involved in?

Vagus nerve visceral sensory component: -*nucleus solitarius* of the medulla [Think Vegas has me all hot and bothered. I need to be alone to deal with these visceral sensations I'm having. I'm coughing so much I might vom!] -1) sensory axons from *trachea, larynx, and other respiratory tubes* travel in vagus -> *cough reflex* -2) sensory axons from *stomach* -> *nausea*, *vomiting reflex*

pic of normal larynx examination -what are the two major functions of the vocal cords of the larynx?

Vocal cords of the larynx: 1) close the airway during swallowing to prevent swallowed objects from entering respiratory passages (aspiration) 2) voice/sound production

Which clinical test could you do for CN IX?

gag reflex! remember it does the sensory arm (vs CN X motor)

-what are the functional components of the glossopharyngeal nerve?

just like vagus!!! 1) Parasympathetic 2) visceral sensory 3) skeletal motor 4) general sensory 5) special sensory - taste

Overview of clinical considerations for vagus nerve: -2 clinical tests? -4 clinical manifestations of damage to this nerve?

know this!