Special Senses I Flashcards
List the cranial nerves.
CN I, Olfactory
CN II, Optic
CN III, Oculomotor
CN IV, Trochlear
CN V, Trigeminal
CN VI, Abducens
CN VII, Facial
CN VIII, Vestibulocochlear
CN IX, Glossopharyngeal
CN X, Vagus
CN XI, Spinal accessory
CN XII, Hypoglossal
What bone structure does the olfactory nerve go through in order to get to the brain?
cribiform plate
Where are the neurons of the olfactory tract found?
nasal cavity
Which structure in the nose catches odorants?
olfactory epithelium
Where in the brain does the olfactory tract first synapse?
primary olfactory cortex (bypasses thalamus)
From the olfactory cortex, where does the olfactory axons synapse?
- amygdala (emotional response to smell)
- hippocampus (memory of smell)
- hypothalamus (sympathetic response to smell)
Which cranial nerve(s) innervate(s) taste?
- CN VII, facial
- CN IX, glossopharyngeal
Which cranial nerve(s) innervate(s) sensation on the tongue?
- CN V, trigeminal
- CN IX, glossopharyngeal
Which cranial nerve(s) innervate(s) movement of the tongue?
CN XII, hypoglossal
What does the hypoglossal nerve control?
Movement of the tongue
What is the main muscle that the hypoglossal nerve innervates? What does this muscle do?
genioglossus mm, sticks out the tongue
Is the genioglossus muscle contralaterally or ipsilaterally innervated? How would a lesion to the hypoglossal nerve present in the muscle?
- ipsilaterally innervated
- tongue deviates to same side of lesion
Through which bone structure does the hypoglossal nerve protrude into the skull?
hypoglossal canal
Through which bone structure does the glossopharyngeal nerve exit from the cranial cavity?
jugular foramen
Which part of the tongue is CN IX responsible for, in terms of taste and touch?
posterior 1/3 of tongue
Which nerve is responsible for sensation of the anterior tongue?
CN V, Trigeminal nerve V3 (mandibular nerve)
Which cranial nerve innervates taste to the anterior 2/3 tongue? posterior 1/3 tongue?
anterior 2/3 tongue taste: CN VII, facial
posterior 1/3 tongue taste: CN IX, glossopharyngeal
Through which bone structure does the facial nerve exit the cranial cavity?
internal acoustic meatus
What is the name of the ganglion in CN VII?
geniculate ganglion
What is the name of the ganglion in CN IX?
inferior ganglion
Which nerve(s) is/are responsible for taste?
VII, IX
Describe the Taste Pathway.
VII, IX –> Nucleus of the solitary tract –> 2nd order neuron project to VPM (thalamus) –> 3rd order neuron project to gustatory cortex
- send collateral branches to amygdala and hippocampus
What is the vestibulocochlear nerve responsible for?
balance/equilibrium and hearing
Through which structure does CN VIII exit the cranial cavity?
internal acoustic meatus
Which 2 nerves join together to form CN VIII? Where are their receptors found?
- cochlea –> cochlear nerve
- semicircular canals –> vestibular nerve
(join up through internal acoustic meatus to form CN VIII, vestibulocochlear)
What kind of fluid is found in the cochlear duct?
endolymph
What kind of fluid is found outside of the cochlear duct?
perilymph
What is the order of sound transmission in the ear (start with ossicles)?
malleus –> incus –> stapes –> oval window –> scala vestibuli –> scala tympani –> cochlear duct –> organ of corti (+ tectorial membrane) –> round window
Are higher sounds detected closer to the outside or inside of the ear?
higher sounds –> closer OUTSIDE
Where in the brain is pitch perceived? comprehended?
perceived: primary auditory cortex (Heschel’s gyri)
comprehended: wernicke’s sensory speech area
Which cranial nerves dampen sound?
VII, V
How does the structure of the auditory pathways allow us to detect where sound is coming from?
BILATERAL auditory pathways –> inter-aural time difference
What are the main parts of the vestibular system?
- saccule
- utricle
- 3 semicircular canals
What is the name for the receptor organ in the semicircular canals? vestibule?
semicircular: cupolae
vestibule: maculae
What kind of information do the utricle and saccule provide?
- head position
- linear acceleration
What kind of info do the semicircular canals provide?
acceleration of the head
Which sensory organ is found in the ampulla?
cupola
When you move your head to the right, which way does the cupola in the ampulla bend?
to the left (opposite)
What 2 structures does the vestibule contain?
utricle and saccule
Which sensory organ in the ear uses otoliths?
macula
(hint: vestibular)
The saccule’s maculae detect:
a) vertical head movement
b) horizontal head movement
a) vertical head movement
The utricle’s maculae detect:
a) vertical head movement
b) horizontal head movement
b) horizontal head movement
Which nucleus in the thalamus does the auditory pathway synapse at?
medial geniculate nucleus
Which complex in the spinal cord allows for sound localization?
superior olivary complex
Are the vestibulospinal tracts descending or ascending pathways?
descending pathways
What are the 2 vestibulospinal tracts?
- lateral vestibulospinal tract
- medial vestibulospinal tract
Which vestibulospinal tract is ipsilateral? bilateral?
lateral = ipsilateral
medial = bilateral
Which vestibulospinal tract is ipsilateral? bilateral?
lateral = ipsilateral
medial = bilateral
Which vestibulospinal tract acts on LMN limbs? LMN axial muscles?
lateral = LMN limbs
medial = axial muscles
Which vestibulospinal tract projects along the medial longitudinal fasciculus?
medial
