Cranial Nerves IX-XII

Question 1

CN XII has its origin where?

Answer 1

In the hypoglossal nucleus

Question 2

What muscle is responsible for tongue protrusion?

Answer 2

The genioglossus muscle

Question 3

Where does CN XII exit the brainstem?

Answer 3

It exits adjacent to the pyramid

Question 4

What is the result of a hypoglossal nerve lesion (lower motor neuron)? (3 things)

Answer 4

1. The tongue deviates towards the lesion
2. Fasciculations
3. Atrophy

Question 5

Does the hypoglossal nerve have corticobulbar fibers?

Answer 5

Yep

Question 6

If you have a corticobulbar (upper motor neuron) lesion, what can you expect to see? (3 things)

Answer 6

1. Deviates toward opposite side
2. No fasciculations
3. Minimal atrophy

Question 7

What is the difference between an upper motor neuron and a lower motor neuron lesion associated with the tongue?

Answer 7

They are basically opposites- upper motor neuron lesions deviate towards the opposite side, no fasciculations and minimal atrophy are observed, and lower motor neurons are exactly the opposite

Question 8

Where is the origin of CN XI?

Answer 8

In the cervical spinal cord, not anywhere on the brainstem

Question 9

What is the result of an accessory nerve lesion? (4 things)

Answer 9

1. Paralyzed trapezius
2. Scapula and clavicle hang due to weak traps
3. Weak shoulder shrug because levator scapulae is left all by itself
4. Muscle atrophy leads to a scalloped appearance of the neck contour

Question 10

For CN IX, which nucleus sends fibers to the skin of the outer ear?

Answer 10

The superior ganglion of IX

Question 11

What are a few structures found in the rostral medulla concerning CN IX?

Answer 11

A lot of CN IX structures:
spinal trigeminal tract & nucleus
Solitary nucleus and tract
Vicinity of the inferior salivatory and ambiguus nuclei

Question 12

What are the CN IX afferents of the skin of the ear and the middle ear as well as taste to the posterior 1/3 of the tongue?

Answer 12

The superior ganglion of CN IX nerve

The trigeminal spinal nucleus

Question 13

CN IX is responsible for taste on what portion of the tongue?

Answer 13

Posterior 1/3

Question 14

The carotid body measures blod O2, CO2 and pH. The carotid sinus monitors changes in blood pressure. What nerve afferents are responsible for conveying this information?

Answer 14

CN IX via the inferior ganglion of CN IX and the solitary nucleus

Question 15

We’ve got some CN IX efferents via the nucleus ambiguus and the inferior salivatory nucleus. What is each responsible for?

Answer 15

Nucleus ambiguus:
- styolopharyngeus muscle and other pharynx and larynx muscles
Inferior salivatory nucleus:
- goes to the otic ganglion and then to the parotid gland

Question 16

What is glossopharyngeal neuralgia?

Answer 16

It’s similiar to trigeminal neuralgia. Sudden bursts of pain start in the posterior tongue or wall of the pharynx which then radiates to the ear. There is a trigger zone on the tongue or pharynx, so attacks are brought on by swallowing or talking.

Question 17

How is glossopharyngeal neuralgia treated?

Answer 17

There are some pills you can take or you can get a tractotomy of the spinal trigeminal tract in the caudal medulla

Question 18

T/F CN IX and X have a lot of similar origins and terminations?

Answer 18

Truth

Question 19

What are a few structures found in the rostral medulla concerning CN X?

Answer 19

Spinal trigeminal nucleus and tract
Dorsal motor nucleus of vagus
Solitary nucleus and tract
Vicinity of the nucleus ambiguus

Question 20

CN X afferents for the skin of the ear are served by what 2 things?

Answer 20

1. Superior ganglion of CN X

2. Trigmeinal spinal nucleus

Question 21

What two types of afferents are found in the epiglottis that are associated with CN X?

Answer 21

Taste

Visceral sensation

Question 22

CN X afferents are also responsible for the aortic arch, baroreceptors, blood pressure and chemoreceptors via which 2 structures?

Answer 22

1. Inferior ganglion of vagus nerve

2. Solitary nucleus of vagus nerve

Question 23

The vagus nerve has many efferents. What are the three things that are innervated via which nuclei?

Answer 23

Nucleus ambiguus (lateral)- muscles of speech and swallowing
Nucleus amiguss (medial)- heart and lungs
Dorsal motor nucleus of the vagus- all viscera up to the transverse colon

Question 24

In the gag reflex, which nerve is the afferent and which nerve is the efferent component of the gag reflex?

Answer 24

Afferent: CN IX
Efferent: CN X

Question 25

Tongue thrust reflex- the efferent limb is from which CN?

Answer 25

CN XII

Question 26

The tongue thrust reflex, if it persists can contribute to what?

Answer 26

Speech and orthodontic issues

Question 27

What is vasovagal syncope?

Answer 27

It is a response to a trigger- the vagus decreases heart rate and blood pressure and the person faints

Question 28

How is vasovagal syncope treated?

Answer 28

With a vagal nerve stimulator

Question 29

What is jugular foramen syndrome?

Answer 29

It is when CN IV, X, XI, XII are at risk of entrapment by a skull base tumor

Question 30

What are some symptoms of Jugular foramen syndrome?

Answer 30

pain in the ear
headache, meningeal irriation
hoarseness
dysphagia
horner syndrom
loss of gag relfex

Question 31

What are the hallmark symptoms (visible signs) of jugular foramen syndrome?

Answer 31

• Uvula deflects to contralateral side
• Inability to adduct vocal cord to midline
• Arch of soft palate droops
• Orophayrngeal sensory loss
• Wasting away of the tongue, deviates to the side of the lesion on protrusion