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The glossopharyngeal nerve (CN IX) emerges from where?
Rostral medulla posterior to the olive
Where does the glossopharyngeal nerve (CN IX) travel after it comes out of the rostral medulla?
Travels intracranially to the jugular foramen from where it exits the skull into the neck
How many modalities are carried by the glossopharyngeal nerve (CN IX)?
5
Can you name all the modalities carried by the glossopharyngeal nerve (CN IX)?
Afferent
  • GSA (General somatic)
  • SVA (General visceral)
  • GVA (Special visceral)
Efferent
  • GVE (General visceral)
  • SVE (Special visceral) 
Can you name the 4 nuclei associated with the glossopharyngeal nerve (CN IX)?
  • Solitary nucleus (surrounding solitary tract)
  • Spinal trigeminal nucleus and tract
  • Nucleus ambiguus
  • Inferior salivatory nucleus
For the solitary nucleus, describe the modality(s) and what is innervated for CN IX?
  • GVA (General visceral afferent)
    -Carotid body (chemoreceptors, baroreceptors)
    -Gag reflex (pharynx)
  • SVA (Special visceral afferent)
    -Taste from posterior 1/3 of tongue
For the trigeminal nucleus describe the modality(s) associated and what is innervated for CN IX?
  • GSA (General somatic afferent)
    -Tongue (posterior 1/3), pharynx, external ear, tympanic membrane 
For the nucleus ambiguus, describe the modality(s) associated and what is innervated for CN IX?
  • SVE (Special Visceral efferent)
    -Stylopharyngeus muscle
This is the only muscle innervated by CN IX. It has the following functions:
  • Elevates larynx, pharynx
  • Dilates the pharynx when swallowing 
For the inferior salivatory nucleus, describe the modality(s) associated and what is innervated for CN IX?
  • GVE (General visceral efferent)
    -Stimulation of parotid gland
The vagus nerve (CN X) emerges from where?
Rostral medulla posterior to olive
  • Inferior to the glossopharyngeal nerve (CN IX)
Where does the vagus nerve (CN X) travel after it comes out of the rostral medulla?
Travels intracranially to the jugular foramen from where it exists the skull into the neck.
How many modalities are carried by the vagus nerve (CN X)?
4
What are the modalities carried by the vagus nerve (CN X)?
Afferent
  • GSA (General somatic)
  • GVA (General visceral)
Efferent
  • SVE (Special visceral)
  • GVE (General visceral)
Can you name the nuclei associated with the vagus nerve (CN X)? (4)
  • Spinal trigeminal nucleus and tract
  • Solitary nucleus and tract
  • Dorsal motor nucleus of vagus
  • Nucleus ambiguus
For the spinal trigeminal nucleus and tract, describe the modality(s) associated and what is innervated for CN X?
  • GSA (General somatic afferent)
    -Posterior meninges, skin of back of ear, external acoustic meatus, pharynx, larynx
For the solitary nucleus and tract, describe the modality(s) associated and what is innervated for CN X?
  • GVA (General visceral afferent)
    -Larynx
    -Thoracic and abdominal viscera
    -Aortic arch (stretch receptors)
    -Aortic bodies (chemoreceptors)
For the dorsal motor nucleus of vagus, describe the modality(s) associated and what is innervated for CN X?
  • GVE (General visceral efferent)
    -Thoracic and abdominal viscera
    -Smooth muscle and glands of pharynx and larynx

Vagus is the parasympathetic efferent for the thoracic and abdominal viscera.
For the nucleus ambiguus, describe the modality(s) associated and what is innervated for CN X?
  • SVE (Special visceral efferent)
    -Pharyngeal muscles
    -Intrinsic muscles of larynx 
Which nucleus associated with the vagus nerve (CN X) provides parasympathetic innervation to cardiac muscle?
Nucleus ambiguus
For accessory nerve (CN XI):
  • What modality is it?
  • Where are the cell bodies of the LMNs?
  • What is the path of the nerves?
  • UMN input to the accessory nerve LMNs comes from where?
  • General Somatic Efferent (GSE)
  • Cell bodies are in the upper cervical levels of the spinal cord (C1 to C5)
  • Motor rootlets enter the skull via foramen magnum, then exit through jugular foramen with CN IX and CN X
  • UMN input to accessory nerve LMNs is through corticobulbar tract
Upper motor neuron (UMN) input to accessory nerve (CN XI) lower motor neurons (LMNs) is through what tract?
Corticobulbar tract
For CN XI, with regard to input through the corticobulbar tract to the SCM muscle and trapezius, which fibers are crossed?
Corticobulbar tract fibers for...
  • Trapezius LMNs: cross over
  • SCM LMNs: stay on ipsilateral side
An UMN lesion of the accessory nerve (CN XI) will lead to what symptoms?
  • Trapezius?
  • SCM? 
UMN, only SCM is ipsilateral:
  • Weakness of trapezius (contralateral)
  • Weakness of SCM muscle (ipsilateral)
LMN lesion of the accessory nerve (CN XI) will lead to what symptoms?
  • Trapezius?
  • SCM? 

LMN, both ipsilateral:
  • Weakness of trapezius (ipsilateral)
  • Weakness of SCM (ipsilateral)
For hypoglossal nerve (CN XII):
  • What is the modality?
  • The cell bodies are located where?
  • What is the path of the nerve?
  • UMN input to the hypoglossal LMNs is through what tract?
  • General somatic efferent (GSE)
  • Cell bodies are in postero-medial in a column in medulla
  • Nerve leaves the medulla anterior to the olive and exits through the hypoglossal canal into the neck
  • UMN input to hypoglossal nerve LMNs is through the corticobulbar tract
For hypoglossal nerve (CN XII), describe the input to LMNs in hypoglossal nucleus of the following structures:
  • Intrinsic muscles of tongue
  • Genioglossus muscle of tongue 

This refers to input from UMNs:
  • Intrinsic muscles: Bilateral
  • Genioglossus: Contralateral
Note: Genioglossus protrudes the tongue
With regard to hypoglossal nerve (CN XII):
  • What would constitute a LMN lesion?
  • What would the effect be? 
  • Damage to neuronal cell bodies in the hypoglossal nucleus or to the axons traveling in the peripheral nerve
  • LMN lesion results in ipsilateral weakness, and contralateral dominance
  • In LMN lesion, when patient protrudes tongue, it protrudes to the side of the lesion
With regard to hypoglossal nerve (CN XII), a UMN lesion:
  • Affects what anatomy?
  • Has what result?
  • Affects the primary motor cortex
  • Remember intrinsic muscles of tongue are bilateral so only genioglossus affected (from contralateral side)
  • Tongue deviates away from the cortical lesion
Name the cranial fossae (3)
  • Anterior cranial fossa
  • Middle cranial fossa
  • Posterior cranial fossa
What defines the volume of the intracranial structures? (3)
  • What can increase the volume? (3)
  • Brain
  • CSF
  • Blood

Things that increase volume:
  • Tumour
  • CSF (eg. hydrocephalus)
  • Blood (eg. bleed) 
What does the falx cerebri do?
  • What is the falx cerebri?
Separates the two hemispheres
  • It is a reflection of the dura 
The tentorium cerebelli isolates what?
It isolates the posterior cranial fossa
  • Sits above the cerebellum
  • Attaches to petrous ridge (laterally)
  • Extends medially to leave an opening for the midbrain 
Name the 3 types of herniations
  • Subfalcine herniation
  • Transtentorial herniation
  • Foramen magnum herniation
Describe a subfalcine herniation
  • What effects does it have? 
Increased ICP pushes one hemisphere towards the other (and under the falx cerebri)
  • Cingulate gyrus pushes under the flax cerebri
  • Leads to occlusion of the anterior cerebral artery on that site
Describe a transtentorial herniation
Increased ICP that pushes onto the tentorium cerebelli
  • Midbrain may be affected
  • Cerebral peduncles and/or CN III may be affected 
Describe a foramen magnum herniation
Increased ICP pushes the brain towards foramen magnum
  • Pressure on medulla
  • Decreased LOC
  • Compromised breathing 
In subfalcine herniation, the anterior cerebral artery can be blocked.
  • What does it supply?
  • Specifically?
The ACA supplies most of the cortex on the medial surface of the frontal and parietal lobes
  • End branches of ACA supply 1 to 2 cm on the lateral surface of the frontal and parietal lobes 
In subfalcine herniation, when there is damage to the anterior cerebral artery what is the important clinical sign?
Weakness of the lower limb on the contralateral side
  • Supplies primary motor areas for lower limb (UMNs) 
In transtentorial (or uncal) herniation, increased ICP pushes onto the tentorium cerebelli
  • What does this cause?
The uncus of the temporal lobe is pushed onto the cerebral peduncles and CN III emerging from the midbrain
In transtentorial herniation, what is the clinical sign when there is pressure on the cerebral peduncles?
Paralysis/weakness on the contralateral side
In transtentorial herniation, what is the clinical sign when there is pressure on CN III?
Parasympathetic fibers to eye are affected first
  • Results in failure to constrict pupil on that sign (i.e. "blown pupil")
In a foramen magnum herniation, what happens?
ICP pushes brain towards foramen magnum
  • Cerebellar tonsils impinge on the medulla
In a foramen magnum herniation, what is the clinical sign?
Breathing center is compromised and the patient is in respiratory distress
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