Special Senses I

Question 1

List the cranial nerves.

Answer 1

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

Question 2

What bone structure does the olfactory nerve go through in order to get to the brain?

Answer 2

cribiform plate

Question 3

Where are the neurons of the olfactory tract found?

Answer 3

nasal cavity

Question 4

Which structure in the nose catches odorants?

Answer 4

olfactory epithelium

Question 5

Where in the brain does the olfactory tract first synapse?

Answer 5

primary olfactory cortex (bypasses thalamus)

Question 6

From the olfactory cortex, where does the olfactory axons synapse?

Answer 6

• amygdala (emotional response to smell)
• hippocampus (memory of smell)
• hypothalamus (sympathetic response to smell)

Question 7

Which cranial nerve(s) innervate(s) taste?

Answer 7

• CN VII, facial
• CN IX, glossopharyngeal

Question 8

Which cranial nerve(s) innervate(s) sensation on the tongue?

Answer 8

• CN V, trigeminal
• CN IX, glossopharyngeal

Question 9

Which cranial nerve(s) innervate(s) movement of the tongue?

Answer 9

CN XII, hypoglossal

Question 10

What does the hypoglossal nerve control?

Answer 10

Movement of the tongue

Question 11

What is the main muscle that the hypoglossal nerve innervates? What does this muscle do?

Answer 11

genioglossus mm, sticks out the tongue

Question 12

Is the genioglossus muscle contralaterally or ipsilaterally innervated? How would a lesion to the hypoglossal nerve present in the muscle?

Answer 12

• ipsilaterally innervated
• tongue deviates to same side of lesion

Question 13

Through which bone structure does the hypoglossal nerve protrude into the skull?

Answer 13

hypoglossal canal

Question 14

Through which bone structure does the glossopharyngeal nerve exit from the cranial cavity?

Answer 14

jugular foramen

Question 15

Which part of the tongue is CN IX responsible for, in terms of taste and touch?

Answer 15

posterior 1/3 of tongue

Question 16

Which nerve is responsible for sensation of the anterior tongue?

Answer 16

CN V, Trigeminal nerve V3 (mandibular nerve)

Question 17

Which cranial nerve innervates taste to the anterior 2/3 tongue? posterior 1/3 tongue?

Answer 17

anterior 2/3 tongue taste: CN VII, facial
posterior 1/3 tongue taste: CN IX, glossopharyngeal

Question 18

Through which bone structure does the facial nerve exit the cranial cavity?

Answer 18

internal acoustic meatus

Question 19

What is the name of the ganglion in CN VII?

Answer 19

geniculate ganglion

Question 20

What is the name of the ganglion in CN IX?

Answer 20

inferior ganglion

Question 21

Which nerve(s) is/are responsible for taste?

Answer 21

VII, IX

Question 22

Describe the Taste Pathway.

Answer 22

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

Question 23

What is the vestibulocochlear nerve responsible for?

Answer 23

balance/equilibrium and hearing

Question 24

Through which structure does CN VIII exit the cranial cavity?

Answer 24

internal acoustic meatus

Question 25

Which 2 nerves join together to form CN VIII? Where are their receptors found?

Answer 25

- cochlea --> cochlear nerve - semicircular canals --> vestibular nerve (join up through internal acoustic meatus to form CN VIII, vestibulocochlear)

Question 26

What kind of fluid is found in the cochlear duct?

Answer 26

endolymph

Question 27

What kind of fluid is found outside of the cochlear duct?

Answer 27

perilymph

Question 28

What is the order of sound transmission in the ear (start with ossicles)?

Answer 28

malleus --> incus --> stapes --> oval window --> scala vestibuli --> scala tympani --> cochlear duct --> organ of corti (+ tectorial membrane) --> round window

Question 29

Are higher sounds detected closer to the outside or inside of the ear?

Answer 29

higher sounds --> closer OUTSIDE

Question 30

Where in the brain is pitch perceived? comprehended?

Answer 30

perceived: primary auditory cortex (Heschel's gyri) comprehended: wernicke's sensory speech area

Question 31

Which cranial nerves dampen sound?

Answer 31

VII, V

Question 32

How does the structure of the auditory pathways allow us to detect where sound is coming from?

Answer 32

BILATERAL auditory pathways --> inter-aural time difference

Question 33

What are the main parts of the vestibular system?

Answer 33

- saccule - utricle - 3 semicircular canals

Question 34

What is the name for the receptor organ in the semicircular canals? vestibule?

Answer 34

semicircular: cupolae vestibule: maculae

Question 35

What kind of information do the utricle and saccule provide?

Answer 35

- head position - linear acceleration

Question 36

What kind of info do the semicircular canals provide?

Answer 36

acceleration of the head

Question 37

Which sensory organ is found in the ampulla?

Answer 37

cupola

Question 38

When you move your head to the right, which way does the cupola in the ampulla bend?

Answer 38

to the left (opposite)

Question 39

What 2 structures does the vestibule contain?

Answer 39

utricle and saccule

Question 40

Which sensory organ in the ear uses otoliths?

Answer 40

macula (hint: vestibular)

Question 41

The saccule's maculae detect: a) vertical head movement b) horizontal head movement

Answer 41

a) vertical head movement

Question 42

The utricle's maculae detect: a) vertical head movement b) horizontal head movement

Answer 42

b) horizontal head movement

Question 43

Which nucleus in the thalamus does the auditory pathway synapse at?

Answer 43

medial geniculate nucleus

Question 44

Which complex in the spinal cord allows for sound localization?

Answer 44

superior olivary complex

Question 45

Are the vestibulospinal tracts descending or ascending pathways?

Answer 45

descending pathways

Question 46

What are the 2 vestibulospinal tracts?

Answer 46

- lateral vestibulospinal tract - medial vestibulospinal tract

Question 47

Which vestibulospinal tract is ipsilateral? bilateral?

Answer 47

lateral = ipsilateral medial = bilateral

Question 48

Which vestibulospinal tract is ipsilateral? bilateral?

Answer 48

lateral = ipsilateral medial = bilateral

Question 49

Which vestibulospinal tract acts on LMN limbs? LMN axial muscles?

Answer 49

lateral = LMN limbs medial = axial muscles

Question 50

Which vestibulospinal tract projects along the medial longitudinal fasciculus?

Answer 50

medial