CN IX-XII

Question 1

What are the nuclei for a glossopharyngeal nerve?

Answer 1

Sensory – nucleus solitarius and spinal nucleus of trigeminal nucleus
Parasympathetic – inferior salivatory nucleus
Motor – nucleus ambiguus

Question 2

Describe attachment of the glossopharyngeal to the brainstem

Answer 2

medulla oblongata posterior to the olive

Question 3

What are the major branches of the glossopharyngeal nerve?

Answer 3

To carotid body and sinus (chemo and baroreceptors)
To stylopharyngeus m.
To tympanic plexus – sensory to middle ear and internal tympanic membrane
Sensory (special and general) to post 1/3 of tongue

Pharyngeal plexus – sensory to the naso-, oro- and laryngopharynx

Question 4

What are the ganglia 9f the glossopharyngeal?

Answer 4

superior (jugular) and inferior (petrosal)

Question 5

Summarize the route of the glossopharyngeal nerve

Answer 5

• Motor to 3rd pharyngeal arch (stylopharyngeus)
• Parasympathetic to parotid gland
• Attaches to the medulla oblongata posterior to the olive
• Has two sensory ganglia: superior (jugular) and inferior (petrosal)

– The inferior ganglion contains the cell bodies carrying input from the carotid sinus
• Exits cranial cavity via jugular foramen

Question 6

What is the nuclei location of the glossopharyngeal nerve?

Answer 6

Nucleus location:
– Sensory–nucleussolitarius and spinal tract of trigeminal nucleus
– Parasympathetic 
– inferior salivatory nucleus
– Motor–nucleus ambiguous

Question 7

Where is the glossopharyngeal insertion located?

Answer 7

Attaches to the lateral portion of the Medulla oblongata

Exiting posterior to the olive

Question 8

Where are the parasympathetics of the glossopharyngeal nerve?

Answer 8

• Parasympathetics
– preganglionic fibers from the inferior salivatory nucleus travel to the otic ganglion

• postganglionic fibers travel with the auriculotemporal branch of the trigeminal nerve
• innervate the parotid glan

Question 9

What are the sensory fibers of the glossopharyngeal nerves?

Answer 9

• Sensory joins the vagus (CN X) to form the pharyngeal plexus

• Sends a branch to the posterior tongue via the tonsillar fossa
– Generalandtastesensation

• Provides visceral afferents from the carotid body and sinus

Question 10

Describe the extracranial course of the glossopharyngeal nerve

Answer 10

• Exits the jugular foramen
• Passes posterior to the carotid sheath and in close association with the cervical sympathetic chain
• Travels along the stylopharyngeus muscle in the tonsillar fossa on its way to the posterior tongue
• Sends branches that join with those of vagus forming the pharyngeal plexus

Question 11

What are the nuclei of the vagus nerve?

Answer 11

Sensory – spinal nucleus of trigeminal nucleus
Parasympathetic – dorsal motor nucleus of vagus
Motor – nucleus ambiguus

Question 12

What are the major branches of the vagus nerve?

Answer 12

Sensory to the external ear canal (in some individuals) Sensory to the larynx, esophagus, bronchus, aortic body and sinus

Motor to the soft palate, larynx and pharynx

Pharyngeal plexus – sensory to the naso-, oro- and laryngopharynx

Parasympathetic to larynx, pharynx, stomach, small intestine, most of large intestin

Question 13

Where does the vagus nerve attach to the brainstem?

Answer 13

medulla oblongata posterior to the olive

Question 14

What are the ganglia of the vagus nerve?

Answer 14

superior and inferior

Question 15

Summarize location of the vagus nerve

Answer 15

• The wanderer/vagabond
• Motor, sensory and parasympathetic
• Attaches to the medulla oblongata dorsal to the olive just inferior to CN IX
• Exits the cranial cavity via jugular foramen

Question 16

What are the nuclei of the vagus nerve?

Answer 16

Nuclei:
– dorsal motor nucleus – parasympathetic
– sensory – nucleus solitarius and spinal
trigeminal
– motor – nucleus ambiguus

Question 17

What is the sensory ganglia of the vagus nerve?

Answer 17

• Sensory ganglia

– superior (nodosum) and inferior ganglion of the vagus

Question 18

Where is the exact attachment of the vagus nerve?

Answer 18

Attaches to the lateral portion of the Medulla oblongata

Exiting posterior to the olive

Question 19

Categorize the different fibers of the vagus nerve

Answer 19

• Motor innervation
– all muscles of the pharynx (except stylopharyngeus), larynx, palatoglossus, the soft palate (except tensor veli palatini)

• General sensation to
– larynx, laryngopharynx, small part of the external auditory
canal

• Visceral afferents
– esophagus, foregut & midgut, bronchi & lungs, heart & aortic body

• Parasympathetics
– smooth muscles & glands of the pharynx, larynx, airways, foregut & midgut

• Special sense: taste
– epiglottis

Question 20

What’s the extracranial course of the vagus nerve?

Answer 20

Exits the jugular foramen
Passes in the carotid sheath
Gives recurrent laryngeal nerve
wraps around SC – right & Aorta – Left

Left and right nerves combines to form esophageal plexus
• Passes through the diaphragm with the stomach
• Divides into an anterior and posterior trunk
• Follows the GI tract down close to the organs

Question 21

How do we test CN IX and X?

Answer 21

• Assess for Dysphonia
– testing muscles of the soft palate (CN X)
• ask patient to say “aaah”

• Coughing & the ear canal
(CN X)
– afferent: touching a part inside the external ear canal may cause coughing
– efferent: larynx (CN X)

• Gagreflex
– afferent: CN IX – efferent: CN X

Question 22

Where does the accessory nerve exit?

Answer 22

Exits upper cervical spinal cord and travels superiorly to pass through the foramen magnum

Question 23

What are the roots of the accessory nerve?

Answer 23

• Two roots:

– medulla (cranial root)
• joins the vagus nerve as it exits
through the jugular foramen
– pharynx, larynx & soft palate

– spinal cord (spinal root)
• rootlets from cervical spinal cord
(C1- C5)
• enters cranial vault through the foramen magnum
• exits through the jugular foramen
• motor: sternocleidomastoid (SCM) & trapeziu

Question 24

What is the extracranial course of the accessory nerve?

Answer 24

Exits the jugular foramen

Travels down the neck along the levator scapulae muscle

Gives branches to the sternocleidomastoid and trapezius muscles

Question 25

How do we assess spinal accessory nerve?

Answer 25

• Lateral head rotation against resistance: SCM

* Shrugging shoulders: trapezius

Question 26

Where does the hypoglossal nerve exit?

Answer 26

Exits ventrally between the pyramid and olive

Question 27

How is the hypoglossal nerve tested?

Answer 27

• Observation
– Fasciculations

• Assess speech
– “yellow lorry”

• Tongue deviation
– Ask patient to “stick out tongue”
– will deviate towards the affected nerve

• Assess tongue strength

Question 28

Where does the hypoglossal nerve run?

Answer 28

• Motor nerve to the muscles of the tongue (except palatoglossus)
• Hypoglossal nucleus located in the medulla oblongata close to the dorsal motor nucleus of the vagus
• Attaches to the brainstem at the sulcus between the olive and pyramid

• Exits cranial cavity through hypoglossal canal
– nerve travels lateral & below the tongue

• C1 (cervical nerve 1) travels with the hypoglossal nerve and goes to the neck
– joins after the hypoglossal canal
– leaves before it innervates the tongue
– innervates thyrohyoid and geniohyoid muscle

Question 29

What are the relationships of the cranial nerve and the dura?

Answer 29

• The cranial nerves pass through the meningeal layer of dura before they pass through the skull
• This means that when looking at the internal aspect of the cranial cavity with the dura intact the visualized exit point of the nerve does not correspond to the foramina in the skull