Cranial Nerves IX-XII Flashcards
CN XII has its origin where?
In the hypoglossal nucleus
What muscle is responsible for tongue protrusion?
The genioglossus muscle
Where does CN XII exit the brainstem?
It exits adjacent to the pyramid
What is the result of a hypoglossal nerve lesion (lower motor neuron)? (3 things)
- The tongue deviates towards the lesion
- Fasciculations
- Atrophy
Does the hypoglossal nerve have corticobulbar fibers?
Yep
If you have a corticobulbar (upper motor neuron) lesion, what can you expect to see? (3 things)
- Deviates toward opposite side
- No fasciculations
- Minimal atrophy
What is the difference between an upper motor neuron and a lower motor neuron lesion associated with the tongue?
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
Where is the origin of CN XI?
In the cervical spinal cord, not anywhere on the brainstem
What is the result of an accessory nerve lesion? (4 things)
- Paralyzed trapezius
- Scapula and clavicle hang due to weak traps
- Weak shoulder shrug because levator scapulae is left all by itself
- Muscle atrophy leads to a scalloped appearance of the neck contour
For CN IX, which nucleus sends fibers to the skin of the outer ear?
The superior ganglion of IX
What are a few structures found in the rostral medulla concerning CN IX?
A lot of CN IX structures:
spinal trigeminal tract & nucleus
Solitary nucleus and tract
Vicinity of the inferior salivatory and ambiguus nuclei
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?
The superior ganglion of CN IX nerve
The trigeminal spinal nucleus
CN IX is responsible for taste on what portion of the tongue?
Posterior 1/3
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?
CN IX via the inferior ganglion of CN IX and the solitary nucleus
We’ve got some CN IX efferents via the nucleus ambiguus and the inferior salivatory nucleus. What is each responsible for?
Nucleus ambiguus:
- styolopharyngeus muscle and other pharynx and larynx muscles
Inferior salivatory nucleus:
- goes to the otic ganglion and then to the parotid gland
What is glossopharyngeal neuralgia?
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.
How is glossopharyngeal neuralgia treated?
There are some pills you can take or you can get a tractotomy of the spinal trigeminal tract in the caudal medulla
T/F CN IX and X have a lot of similar origins and terminations?
Truth
What are a few structures found in the rostral medulla concerning CN X?
Spinal trigeminal nucleus and tract
Dorsal motor nucleus of vagus
Solitary nucleus and tract
Vicinity of the nucleus ambiguus
CN X afferents for the skin of the ear are served by what 2 things?
- Superior ganglion of CN X
2. Trigmeinal spinal nucleus
What two types of afferents are found in the epiglottis that are associated with CN X?
Taste
Visceral sensation
CN X afferents are also responsible for the aortic arch, baroreceptors, blood pressure and chemoreceptors via which 2 structures?
- Inferior ganglion of vagus nerve
2. Solitary nucleus of vagus nerve
The vagus nerve has many efferents. What are the three things that are innervated via which nuclei?
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
In the gag reflex, which nerve is the afferent and which nerve is the efferent component of the gag reflex?
Afferent: CN IX
Efferent: CN X
Tongue thrust reflex- the efferent limb is from which CN?
CN XII
The tongue thrust reflex, if it persists can contribute to what?
Speech and orthodontic issues
What is vasovagal syncope?
It is a response to a trigger- the vagus decreases heart rate and blood pressure and the person faints
How is vasovagal syncope treated?
With a vagal nerve stimulator
What is jugular foramen syndrome?
It is when CN IV, X, XI, XII are at risk of entrapment by a skull base tumor
What are some symptoms of Jugular foramen syndrome?
pain in the ear headache, meningeal irriation hoarseness dysphagia horner syndrom loss of gag relfex
What are the hallmark symptoms (visible signs) of jugular foramen syndrome?
- 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
