Exam #2: Cranial Nerves V Flashcards
What is the functional component of the cochlear nerve?
SSA (Special Somatic Afferent)–hearing
Where are the cell bodies of the 1st order neurons of the auditory pathway located?
Cochlear/ Spiral Ganglion
Where do the dendrites of the cochlear ganglion terminate?
Receptor hair cells of the Organ of Corti
Where do the axons of the cochlear ganglion enter the brain? What happens here?
Pons–axons bifurcate & go to either:
1) Dorsal cochlear nucleus
2) Ventral cochlear nucleus
Where are the second order neurons of the auditory pathway located?
1) Dorsal cochlear nucleus
2) Ventral cochlear nucleus
BOTH of which are in the Pons
What do the axons of the Ventral Cochlear Nucleus form? Where do these axons project?
Axons of the Ventral Cochlear Nucleus form the “Ventral Acoustic Stria” or “Trapezoid Body.” These axons go to:
1) Nucleus of the Trapezoid Body
2) Superior Olivary Nucleus
Others ascend in the lateral lemniscus (LL) & terminate in:
Nucleus of the LL to INFERIOR COLLICULUS
What do the axons of the Dorsal Cochlear Nucleus form? Where do these axons project?
Axons of the Dorsal Cochlear Nucleus form the “Dorsal Acoustic Stria” that ascend the Lateral Lemniscus (LL) & terminate in the INFERIOR COLLICULUS
What auditory nucleus sends projections to the superior olivary nucleus?
Ventral Cochlear Nucleus
What is the function of the superior olivary nucleus in regards to hearing?
Localization of sound
What is the main pathway of hearing after BOTH the Ventral & Dorsal Cochlear Nuclei?
Axons synapse on the Lateral Lemniscus, which projects to the inferior colliculus of the midbrain
What is the function of the inferior colliculus in regards to hearing?
This is the relay nucleus for hearing in the midbrain
Where does the inferior colliculus project?
Medial Geniculate Nucleus (MGN) of the Thalamus
What is the function of the MGN?
Processing of sound INTENSITY & FREQUENCY
Where does the MGN project?
Auditory cortex via the “auditory radiation”
What Brodmann’s areas comprise the primary auditory cortex?
41 & 42
What is the function of the primary auditory cortex in hearing?
- Localization of sound
- Detecting alterations of the pattern of sound
Where else does the MGN project besides the primary auditory cortex? What is the function of these projections?
Secondary cortical areas, which is important for interpretation of:
- Sound
- Voice
- Language
- Music
What are the 3rd order neurons of the auditory pathway?
Superior olivary nucleus
Where is the sensory information to the Superior Olivary Nucleus coming from?
BOTH ears
What is the sound attenuation reflex?
Protective reflex that causes contraction of the tensor tympani & stapedius, dampening auditory input
Outline the neuronal pathway of the sound attenuation reflex.
1) Loud sound at hair cells (organ or corti)
2) Transduction down dendrites of chochlear ganglia
3) Axons of cochlear ganglia project to the ventral cochlear nucleus
4) Ventral cochlear nucleus projects to the superior olivary nucleus
5) Superior olivary nucleus projects onto BOTH the TRIGEMINAL & FACAL NUCLEI
What muscle is innervated by the trigeminal nerve in the sound attenuation reflex?
Tensor tympani
What muscle is innervated by the facial nerve in the sound attenuation reflex?
Stapedius
What is the functional component of the vestibular nerve?
SSA (Special Somatic Afferent)–Equilibrium
What ganglia contains the first order neurons of the vestibular pathway?
Vestibular ganglia or “Scarpa’s Ganglia”
Where are the dendrites of the vestibular ganglia?
1) Hair cells of the maculae or the utricle & saccule
2) Cristae of the semicircular canal ampullae
Where do the axons of the vestibular ganglia project?
- Pons, where they bifurcate & synapse with:
1) Vestibular nuclei
2) Inferior cerebellar peduncle, where they end in the flocculonodular lobe of the cerebellum
What is the flocculonodular lobe of the cerebellum? Why is this important?
This is the region of the cerebellum that coordinates head & eye movement
*****This connection makes the vestibular nerve the ONLY nerve to have a direct connection to the cerebellum
Where are the second order cell bodies of the vestibular pathway located?
Vestibular nuclei
Where do the axons of the vestibular nuclei project?
- These axons join the Medial Longitudinal Fasiculus (MLF)_ to project to the:
1) Extraocular muscle nuclei
2) Reticular formation
3) Cervical spinal cord - Other axons terminate in the cerebellum & thalamus
*****Note that the thalamus contains the 3rd order neurons
Where are the cell bodies of the third order neurons of the vestibular pathway located?
VPL & VPI nuclei of the Thalamus
Where do the third order neurons of the vestibular pathway project?
Primary vestibular cortex
What Broadmann’s area is the Primary Vestibular Cortex?
3a
*****Note that this is the medial surface of the postcentral gyrus
What are the functional components of the glossopharyngeal nerve?
GVA (General Visceral Afferent) SVA (Special Visceral Afferent) GVE (General Visceral Efferent) SVE (Special Visceral Efferent) GSA (General Somatic Afferent)
What are the GVA inputs carried by the glossopharyngeal nerve (CN IX)?
- Pharyngeal tube
- Palatine tonsils, fauces
- Pharynx
- Carotid sinus (baroreceptor)
What is the SVA component of the glossopharyngeal nerve (CN IX)?
Taste from the posterior 1/3 of the tongue
What is the GVE component of the glossopharyngeal nerve (CN IX)?
PNS to the:
1) Parotid gland
2) Minor salivary glands of the tongue & pharynx
What is the SVE component of the glossopharyngeal nerve (CN IX)?
Skeletal motor innervation of the stylopharyngeus muscle
What is the GSA component of the glossopharyngeal nerve (CN IX)?
Sensation from the:
1) Ear
2) Ear canal
3) Posterior 1/3 of the tongue
What are the two sensory ganglia associated with the glossopharyngeal muscle?
Superior & inferior ganglia of the glossopharyngeal nerve
Where do the axons of the superior ganglia of the glossopharyngeal nerve project?
Spinal V Nucleus (via the Spinal V tract)
*****This ganglia is involved in NOCICEPTION
Where do the axons of the inferior ganglia of the glossopharyngeal nerve project?
Solitary nucleus via the solitary tract
What PNS ganglia is associated with the glossopharyngeal nerve (CN IX)?
Otic ganglia
What does the Otic ganglion contain?
POST-synaptic PNS fibers to the parotid gland
What are the three nuclei associated with the glossopharyngeal nerve (CN IX)?
1) Inferior salivatory nucleus
2) Nucleus ambiguous
3) Solitary nucleus
What does the inferior salivatory nucleus contain?
Cell bodies of PRE-synaptic PNS neurons that synapse with the otic ganglion
What does the nucleus ambiguious contain? What important function is this nuclei involved in?
Cell bodies of motor neurons to the stylopharyngeus muscle
*****Swallowing
What axons does the solitary nucleus receive?
Axons of sensory (i.e. both GVA & SVA) fibers
What is Frey’s Syndrome?
This is someone that sweats instead of salivating
- Caused by damage to POST-synaptic PNS glossopharyngeal nerve (CN IX) nerves that sprout, regeneration, and get “lost”
- Innervate sweat glands instead of salivary
**Can be caused by parotid reconstruction surgery
What are the characteristic deficits seen with a lesion to the glossopharyngeal nerve?
1) Loss of taste from posterior 1/3 of tongue
2) Decreased salivation
3) Diminished visceral sensation
4) Loss of gag reflex
5) Loss of carotid sinus reflex
What are the five functional components of the vagus nerve?
GVA (General Visceral Afferent) SVA (Special Visceral Afferent) GVE (General Visceral Efferent) SVE (Special Visceral Efferent) GSA (General Somatic Afferent)
What are the GVE functions of the vagus nerve (CN X)?
PNS to thorax & abdomen
What are the SVE functions of the vagus nerve (CN X)?
Skeletal motor to pharyngeal & laryngeal skeletal muscles
What are the SVA functions of the vagus nerve (CN X)?
Taste from the epiglottis, soft palate, & upper pharynx
What are the GSA functions of the vagus nerve (CN X)?
Sensation from the outer ear, external auditory meatus, & posterior 1/3 of the dura
What are the GVA functions of the vagus nerve (CN X)?
Sensation from the mucous membrane of the soft palate, pharynx, esophagus, larynx, trachea, carotid body
What nuclei are associated with the vagus nerve?
1) Dorsal motor nucleus of the vagus
2) Nucleus ambiguus
3) Solitary nucleus
What is associated with the dorsal motor nucleus of the vagus?
PNS
Pregnanglionic PNS neurons
WHat is associated with the nucleus amgibuus of the vagus nerve?
Skeletal motor
Skeletal muscles
What is associated with the solitary nucleus of the vagus?
Receives taste & visceral sensory neurons
What are the three ganglia associated with the vagus nerve?
1) Superuir ganglia
2) Inferior (nodose) ganglia
3) PNS
What are the characteristic deficits seen with a lesion to the glossopharyngeal nerve?
1) Loss of taste from posterior 1/3 of tongue
2) Decreased salivation
3) Diminished visceral sensation
4) Loss of gag reflex
5) Loss of carotid sinus reflex
What are the five functional components of the vagus nerve?
GVA (General Visceral Afferent) SVA (Special Visceral Afferent) GVE (General Visceral Efferent) SVE (Special Visceral Efferent) GSA (General Somatic Afferent)
What are the GVE functions of the vagus nerve (CN X)?
PNS to thorax & abdomen
What are the SVE functions of the vagus nerve (CN X)?
Skeletal motor to pharyngeal & laryngeal skeletal muscles
What are the SVA functions of the vagus nerve (CN X)?
Taste from the epiglottis, soft palate, & upper pharynx
What are the GSA functions of the vagus nerve (CN X)?
Sensation from the outer ear, external auditory meatus, & posterior 1/3 of the dura
What are the GVA functions of the vagus nerve (CN X)?
Sensation from the mucous membrane of the soft palate, pharynx, esophagus, larynx, trachea, carotid body
What nuclei are associated with the vagus nerve?
1) Dorsal motor nucleus of the vagus
2) Nucleus ambiguus
3) Solitary nucleus
What is associated with the dorsal motor nucleus of the vagus?
PNS
Pregnanglionic PNS neurons
WHat is associated with the nucleus amgibuus of the vagus nerve?
Skeletal motor
Skeletal muscles
What is associated with the solitary nucleus of the vagus?
Receives taste & visceral sensory neurons
What are the three ganglia associated with the vagus nerve?
1) Superuir ganglia
2) Inferior (nodose) ganglia
3) PNS