CN IX-XII Flashcards
What are the nuclei for a glossopharyngeal nerve?
Sensory – nucleus solitarius and spinal nucleus of trigeminal nucleus
Parasympathetic – inferior salivatory nucleus
Motor – nucleus ambiguus
Describe attachment of the glossopharyngeal to the brainstem
medulla oblongata posterior to the olive
What are the major branches of the glossopharyngeal nerve?
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
What are the ganglia 9f the glossopharyngeal?
superior (jugular) and inferior (petrosal)
Summarize the route of the glossopharyngeal nerve
- 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
What is the nuclei location of the glossopharyngeal nerve?
Nucleus location: – Sensory–nucleussolitarius and spinal tract of trigeminal nucleus – Parasympathetic – inferior salivatory nucleus – Motor–nucleus ambiguous
Where is the glossopharyngeal insertion located?
Attaches to the lateral portion of the Medulla oblongata
Exiting posterior to the olive
Where are the parasympathetics of the glossopharyngeal nerve?
• 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
What are the sensory fibers of the glossopharyngeal nerves?
• 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
Describe the extracranial course of the glossopharyngeal nerve
- 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
What are the nuclei of the vagus nerve?
Sensory – spinal nucleus of trigeminal nucleus
Parasympathetic – dorsal motor nucleus of vagus
Motor – nucleus ambiguus
What are the major branches of the vagus nerve?
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
Where does the vagus nerve attach to the brainstem?
medulla oblongata posterior to the olive
What are the ganglia of the vagus nerve?
superior and inferior
Summarize location of the vagus nerve
- 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
What are the nuclei of the vagus nerve?
Nuclei:
– dorsal motor nucleus – parasympathetic
– sensory – nucleus solitarius and spinal
trigeminal
– motor – nucleus ambiguus
What is the sensory ganglia of the vagus nerve?
• Sensory ganglia
– superior (nodosum) and inferior ganglion of the vagus
Where is the exact attachment of the vagus nerve?
Attaches to the lateral portion of the Medulla oblongata
Exiting posterior to the olive
Categorize the different fibers of the vagus nerve
• 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
What’s the extracranial course of the vagus nerve?
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
How do we test CN IX and X?
• 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
Where does the accessory nerve exit?
Exits upper cervical spinal cord and travels superiorly to pass through the foramen magnum
What are the roots of the accessory nerve?
• 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
What is the extracranial course of the accessory nerve?
Exits the jugular foramen
Travels down the neck along the levator scapulae muscle
Gives branches to the sternocleidomastoid and trapezius muscles
How do we assess spinal accessory nerve?
- Lateral head rotation against resistance: SCM
* Shrugging shoulders: trapezius
Where does the hypoglossal nerve exit?
Exits ventrally between the pyramid and olive
How is the hypoglossal nerve tested?
• Observation
– Fasciculations
• Assess speech
– “yellow lorry”
• Tongue deviation
– Ask patient to “stick out tongue”
– will deviate towards the affected nerve
• Assess tongue strength
Where does the hypoglossal nerve run?
- 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
What are the relationships of the cranial nerve and the dura?
- 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
