2nd half of CN lecture Flashcards
Is CN VII motor, sensory, or both?
Both
You know that CN VII mediates facial expression by motor to muscles, but what 2 parasympathetic actions does it carry?
Salivation and lacrimation
What are the two main areas of sensory for CN VII?
Behind the ear/ concha and the anterior 2/3 of the tongue
How many branches are there of the facial nerve and what are their names?
- Temporal, Zygomatic, Buccal, Mandibular, Cervical To Zanzibar By Motor Car
What are the 3 ganglions associated with CN VII? (2 in one
Geniculate Ganglion - Pterygopalatine ganglion - Lacrimal gland Geniculate Ganglion - Submandibular ganglion - Submandibular/ sublingual glands
What is the pathway of facial motor nerves?
Facial motor nucleus - VII nerve - IAC - Facial Canal - Stylomastoid Foramen - passes through the parotid gland - muscles
True/False: CN VII has bilateral innervation the for whole face.
False. Bilateral is only the forehead. Stroke (UMN) will have forehead sparing, Bell’s Palsy (LMN) won’t.
Describe the special sensory components
Taste from Lingual N to Chorda Tympani to Facial N
CN VII is involved in the corneal blink reflex. Efferent or afferent?
Efferent (exit) Afferent is V1
If you have abnormal taste on the anterior 2/3 of the tongue, where would the lesion be?
Lingual N or Chorda Tympani
Hyperacusis (sensitivity to certain frequencies/ volume) can happen with paralysis of ______ muscle
Stapedius
Bell’s Palsy is a LMN lesion of CN VII. What would you expect to see?
Paralysis and possibly atrophy of the muscles of facial expression Uncontrolled tearing Lips cannot be held together and food will spill out on affected side Loss of the efferent limb of the CORNEAL REFLEX - cannot close eye
It matters if you cut above or below where the Chorda tympani joins the lingual nerve. Why?
Cut Lingual N ABOVE where chorda tympani joins spares CN VII and only cuts CN V.
You would spare taste, but lose general sensation from anterior 2/3
A Schwannoma can effect what 2 nerves?
CN VII and CN VIII
Vestibulocochlear Nerve VIII exits the brain stem at the ____________ _______ and enters _____ _____ ____into the _______ ____
Cerebellopontine Angle Internal Auditory Canal Petrous Bone
Cn VIII regulates compensatory eye movements via what?
Think about where CN III, IV, and VI go.
Medial Longitudinal Fasciculus
How would you test CN VII?
–Observe nystagmus during EOM Test
–Romberg Test: Patient falls to side of vestibular hypofunction
•Also seen in dorsal column disease - Lues
–Caloric Testing
–Coordination Examinations
Name 3 lesions of CN VIII
–Acoustic Neuroma and aneurysms
–Meningiomas
–MS
Describe bone and air conduction. Where and how are those waves transmitted? Which do you expect to be louder?
- Conductive hearing loss: Disorder of the external and/or middle ear impairing conduction of sound to the inner ear.
- Sensorineural hearing loss: Disorder of the inner ear, cochlear nerve, or its central connections impairing transmission of nerve impulses to the brain.
- Air conduction describes the normal hearing pathway from the external ear to the junction of the middle and inner ear.
- Bone conduction bypasses the external and middle ear. The bones of the skull vibrate and stimulate the cochlea directly.
- Normally, air conduction is more sensitive than bone conduction
What are the two tests to study for bone and air conduction?
Weber and Rinne
What is the area where the ossicles are held called?
Vestibule (antechamber)
If you get a tumor on CN VIII what 3 symptoms would you have?
Deafness, Vertifo, Tinnitis
Glossopharyneal CN IX mediates what?
taste, salivation, and swallowing
CN IX is M, S, or B?
Where does it exit the skull?
Both!
Jugular Foramen
What are the sensory components of CN XI?
Carotid Body Chemoreceptors/ Baroreceptors (Afferent for carotid sinus reflex)
Sensory from the oropharynx, posterior 1/3 of tongue, palatine tonsils, oropharynx, middle ear, and pharyngotympanic tube (Eustachian Tube) (Afferent for Gag reflex)
What are the 2 motor componets of CN IX that we don’t test for?
–Stylopharyngeus muscle
–General Visceral Efferents
•The Parasympathetic Component that Innervates the Parotid Salivary Gland
We do test the sensory portion of CN IX though! How do we do it?
You politely ask to gag your patient to test CN IX and X. It also has taste/ general sensation for posterior 1/3 of the tongue.
What would happen with a leasion of CN IX?
–Loss of Gag reflex (interrupted afferent limb, efferent limb is the Vagus Nerve CN X))
–Problem swallowing
–Loss of sensation, including taste, from the oropharynx, soft palate, tonsils, posterior 1/3 of tongue, and pharyngeal walls
–Loss of carotid sinus reflex (loss of the afferent limb)
The vagus (wandering) nerve CN X goes a lot further than the other CNs. What does CN X innervate?
viscera of the neck, thorax, and abdomen
CN X exits the brainstem from the medulla and exits the skull via what foramen?
Jugular
CN X is both sensory and motor. Where would this wandering nerve have sensory components?
- Sensory from the Aortic Body chemoreceptors
- Sensory from the Aortic Arch baroreceptors
- Sensory from laryngopharynx, larynx, esophagus, bronchi, lungs, heart, and foregut and midgut abdominal viscera
- Sensory from skin posterior to ear and external auditory meatus, and dura in posterior cranial fossa
- Taste from the Epiglottis
What are the motor components of CN X? Think aboout both parasympathetic and non-parasympathetic.
–Parasympathetic - General Visceral
•Efferents: Innervates smooth muscle and glands in the laryngopharynx, larynx, thoracic viscera, and foregut and midgut abdominal viscera
–Visceral Motor Efferents -
- Mediates swallowing and phonation
- Innervates muscles of the Soft Palate (except Tensor Veli Palatini)
- Innervates muscles of Pharynx
- Innervates the Larynx via the Recurrent Laryngeal Nerves
- Is the EFFERENT LIMB OF THE GAG REFLEX - tongue retraction, elevation and constriction of the pharyngeal musculature
Name the four muscles, what they do, and what nerve innervates them.
Tensor:
Tensor Veli Palatini: V3 - Opens the Eustachian Tube “Pops the ears”
Elevator:
Levator Veli Palatini X “Ahhhh” muscle
Depressor:
Palatopharyngeus X
Palatoglossus X
Elevator of Uvula:
Musculus Uvulae X
WTF is the musculus Uvulae
Best I could find. I think it is the uvula itself?
We make people say Ahh for symmetrical elevation of the soft palate arches, aka. ______ ______, and Gag them to test CN X(Affernt or Efferent?)
What would a deviation to the side indicate?
What does hoarseness or Stridor make you think about?
Palatal Reflex
Efferent
Paralysis of the LEVATOR VELI PALATINI - ipsilateral paralysis of the soft palate and pharynx with damage to CN X
Vocal Cord Paralysis - Recurrent Laryngeal N (Gallicurci)
Hoarseness is unilateral / Stridor is bilateral (IMMEDIATE ATTENTION)
CN X travels throught the ______________ tract before decussation and synapsing in the _________ _________ and then innervating palatal arches.
corticobulbar tract/ Nucleus ambiguus (Biggus Dickus from Life of Brian)
In lab all we can see is a thick nerve because the branches are easily dissected off. After the Inferior Ganglion CN X has 4 branches in the neck, then the recurrent laryngeal nerve. What are those 4 branches?
Pharyngeal Branch
Carotid Body Branch
Internal/ External Branches of Superior Laryngeal nerve
Recurrent Laryngeal N. Left goes under ______. Right goes under ______
Left goes under Aortic Arch. Right goes under Right Subclavian Artery
The carotid sinus and aortic arch transmits via CN IX and CN X to the ______ nucleus of the ______
Solitary nucleus of the medulla
CN X caries what kind of information to the solitary nucleus?
Increase or decrease in BP
CN __ innervates the carotid sinus/ baro receptors
CN __ innervates the aortic carotid/ baro receptors
CN IX
CN X
If you stimulate the carotidd bodies (caotid sinus massage), you stimulate hypertension. Describe what happens next.
↑ baroreceptor firing → ↑ AV node refractory period → ↓ HR and Cardiac output
Travels via CN IX (X for aortic) to the solitary nucleus
What is the Cushing reflex/ reaction mediated by the Central Medullary Baroreceptors?
Increased intracranial pressure constricts arterioles, causing cerebral ischemia, reflex hypertension, and reflex bradycardia
Mediated by Central Medullary Barorecptors
What do Chemoreceptors regulate?
Respiratory activity. CO2 is important for pH
You have central and peripheral chemoreceptors. What do each of them sense and where are they?
Central:
•Central Medullary Chemoreceptors: sensitive to pH and PCO2, (arterial CO2) NOT sensitive to PO2
Peripheral:
Carotid body and Aortic arch receptors: respond to low PO2 (<60 mm Hg), high PCO2, and low blood pH.
Spinal Accessory Nerve XI is motor, sensory, or both?
Motor: head and shoulder movements
CN XI exits the _____ foramen. The spinal portion arrises from C__ to C___
Jugular. C1-C6
CN Xi innervates these 2 mm.
Sternoclediomastoid and Trapezius
Jugular foramen tumors would impinge what 3 CNs? What kind of tumors would these be?
CN IX, X, and XI
Meningiomas and Glomus (Paraganglioma) Tumors.
Glomus tumors cells are chemoreceptor cells, similar to the carotid body cells.
The last CN! Hypoglossal is CN XII and is (M,S, or B) to the _____
Motor to the tongue
What are the four muscles of tongue movement and what nerve innervates them?
CN X - Palatoglossus
CN XII - Hyoglussus, Genioglossus, Styloglossus
We test the integrity by having the pt,. stick out the tongue. It will deviate the the weak side.
A LMN lesion will deviate the tongue (toward/away from) the lesion
An UMN lession will deviate the tongue (toward/away from) the lesion
Toward LMN (Fasciculations/ atrophy)
Away from UMN (Corticobulbar. NO Fasciculations/ atrophy)
(Hemiparalysis. Slurred speach with both)
What two bones do the root of the tongue attach to?
Mandible and Hyoid Bone
The vestibulo-ocular Reflex is tested with the Doll’s eyes phoneomena: What is a positive and what does it mean?
Testing CN III, IV, and VIII nuclei in the brainstem. A positive sign would show eye movement opposite head movement and means there is an INTACT brain stem.
Brief, intense pain (sharp, stabbing, burning) on one side of the throat that may radiate to the mouth or ear can be caused by what kind of tumor?
Glossopharyngeal Neuralgia - rare
Also called Vagoglossopharyngeal Neuralgia
Glossopharyngeal Neuralgias can be caused by what?
Vascular impressions on CN IX or CN X or by tumors or rarely Multiple Sclerosis
