Sensory Cranial Nerves - V, VII, VIII, IX, X

Question 0

The sulcus limitans forms the outer margin of what structure in the adult?

Answer 0

Outer margin of the floor of the fourth ventricle

Question 1

Which cranial nerves (other than I and II) have sensory components? (5)

Answer 1

V, VII, VIII, IX, X

Question 2

What is unique about the location of the spinal nucleus of V? Which 4 cranial nerves project to it?

Answer 2

It extends as a column from the mesencephalon to the spinal cord (is continuous with the substantia gelatinosa of the spinal cord at that point); V, VII, IX, X

Question 3

Which 3 CNs project to the nucleus Solitarius?

Answer 3

VII, IX, X - rostral part is concerned with taste

Question 4

Where do axons from the nasal epithelium that are part of CN I synapse? WhT are they known as after that?

Answer 4

Olfactory bulb - then project as olfactory tract to olfactory cortex, amygdala and other forebrain structures

Question 5

_________ is the loss of the sense of smell.

Answer 5

Anosmia

Question 6

CN II is made of axons of ______ _______ cells.

Answer 6

Retinal ganglion (cells)

Question 7

Optic nerves from each eye converge just outside the __________. Central to the optic chiasm, the fibers run as the optic ______.

Answer 7

Mesencephalon; tract

Question 8

What structure does the optic tract run through on its way to. The primary visual cortex?

Answer 8

Lateral geniculate body (visual thalamus)

Question 9

Optic nerve fibers bypassing the lateral geniculate nucleus that travel to the superior colliculus are important for what?

Answer 9

Visual “startle” reflexes

Question 10

V1=?, V2=?, V3=? What kind of sensory info is carried by trigeminal nerves?

Answer 10

V1= opthalmic nerve
V2= maxillary nerve
V3= mandibular nerve
*carry epicritic (fine touch, proprioception) and protopathic (pain and temperature)

Question 11

What innervates the back of the head?

Answer 11

Spinal nerves from C2

Question 12

Which nucleus relieves epicritic afferents from the face? (Fine touch, vibration sense)

Answer 12

Chief sensory nucleus of V (located in rostral pons)

Question 13

Where do epicritic afferents in the face region have their cell bodies located?

Answer 13

Trigeminal (Gasserian) ganglion

* is analogous to DRG

Question 14

What other 3 nerves other than V also carry afferents with fine touch afferents? Where do they synapse?

Answer 14

VII, IX, X –> Chief sensory nucleus of V, it is this the first integration center for all fine touch and vibration inputs to the face (epicritic info)

Question 15

Which nucleus contains the cell bodies of proprioceptive afferents from the muscles of mastication? Location?

Answer 15

Mesencephalic nucleus of V; located in the Tegmentum of the mesencephalon
*is essentially a displaced peripheral ganglion

Question 16

What nucleus receives protopathic (pain and temp) afferents from face? Other than V, what 3 other CNs also bring their protopathic afferents to synapse there?

Answer 16

Spinal nucleus of V; VII, IX, X

Question 17

Where do protopathic afferents in V have their cell bodies located?

Answer 17

Trigeminal ganglion

Question 18

What is the tract that runs from the chief sensory nucleus of av to the VPM of thalamus?

Answer 18

Trigeminal leminiscus —> takes epicritic input, is therefore analogous to the posterior column/medial leminiscus for spinal pathways
* pathway passes to contralateral side before synapsing in the VPM

Question 19

What is the name for the tract between the spinal nucleus of V to the VPM of the thalamus?

Answer 19

Trigeminothalamic tract—-> carries protopathic fibers

* 2nd order neurons are contralateral by the time they synapse in the VPM

Question 20

Afferents from which 3 CNs are located most dorsally in the spinal tract and nucleus of V?

Answer 20

VII, IX, X; then V3, V2, V1—> as goes from dorsal to ventral

Question 21

What two sensory components does VII have?

Answer 21

Taste: anterior 2/3 of tongue

Somesthetic afferents: for small area around the external auditory meatus (fine touch, vibration, pain, and temperature)

Question 22

Where are cell bodies for somesthesic afferents of CN VII located?

Answer 22

Geniculate ganglion

Question 23

From the geniculate ganglion what nucleus do epicritic fibers of VII project to? Protopathic fibers?

Answer 23

From geniculate ganglion:

• epicritic : chief sensory nucleus of V
• protopathic: spinal nucleus of V

Question 24

What is the rostral portion of the nucleus solitarius known as? What three CNs does it receive input from?

Answer 24

Gustatory nucleus
CN VII : anterior 2/3 of tongue
CN IX : posterior 1/3 of tongue
CN X : pharynx and epiglottis

Question 25

What is the caudal part of the solitary nucleus known as?what kind of input does it receive?

Answer 25

Cardio respiratory nucleus—> receives visceral sensory input (glands, chemoreceptors, baroreceptors) carried by VII, IX, X

Question 26

CN VIII has a sensory component with what two divisions?

Answer 26

1. Vestibular –> balance and acceleration (body position in space)
2. Auditory –> hearing
   * both located in the inner ear

Question 27

What organ are auditory receptors found on in the cochlea?

Answer 27

Organ of Corti

* the receptors are called hair cells

Question 28

What kind of cells are vestibular receptors? In what three places are they located?

Answer 28

Hair cells ; located in—>

1. Saccule
2. Utricle
3. 3 semicircular canals

Question 29

In what ganglion are cell bodies of auditory afferents located? Where do they synapse?

Answer 29

Spiral ganglion—> dorsal and ventral cochlear nuclei

• synapse ipsilaterally; cochlear nuclei found at the pontomedullary junction

Question 30

From the dorsal and ventral cochlear nuclei, what two structures do auditory afferents pass through to reach the auditory cortex (Heschel’s gyrus, transverse gyrus in temporal lobe)

Answer 30

Inferior colliculus—> medial geniculate body (auditory thalamus)

Question 31

The vestibular division of CN VIII is responsible for what three functions?

Answer 31

1. Adjustment of posture
2. Regulating muscle tone
3. Coordination of eye movements

Question 32

What ganglion do vestibular hair cells synapse on?

Answer 32

Vestibular (Scarpa’s) ganglion –> these send their axons in the vestibular division of the vestibululocochlear nerve

Question 33

Axons leaving the vestibular ganglion synapse in the vestibular nuclei, which four are there?

Answer 33

Superior, lateral, medial, inferior

Question 34

What are the 2 functions of the lateral vestibulospinal tract, coming from the lateral vestibular nucleus?

Answer 34

Controls balance and extensor tone

Question 35

What is the function of the medial vestibulospinal tract that arises from the medial and inferior vestibular nuclei?

Answer 35

Controls head and neck position (only extends to cervical levels of the cord)

Question 36

What is the function of the medial longitudinal fasciculus, which arises from medial and superior vestibular nuclei?

Answer 36

Is important for coordinating eye movements

Question 37

Afferents from carotid sinus (baroreceptors) and carotid body (chemoreceptors) are carried by CN IX and project to where (what nucleus)?

Answer 37

Caudal part of the solitary nucleus and tract

Question 38

From where does CN X carry info from baroreceptors and chemoreceptors ?

Answer 38

Aortic arch

Question 39

From where does CN X carry protopathic info from?

Answer 39

Small portion of external ear; also from posterior meninges

Question 40

What CN mediates the afferent limb of the gag reflex? To what nucleus do they project?

Answer 40

CN IX –> caudal solitary nucleus

Question 41

In which nucleus is the interneuron between the afferent and efferent parts of the Gag reflex?

Answer 41

Nucleus ambiguous

Question 42

What CN mediates the efferent response of the gag response?

Answer 42

CN X (motoneurons from N. Ambiguous whose axons travel with CN X)