Gustatory system

Question 1

Secondary neuroepithelial taste receptor

Answer 1

in taste buds
chemoreceptors
innervated by: facial, glossopharyngeal and vagus

Question 2

Nerves

Answer 2

anterior 2/3: lingual nerve (V/3) + chorda tympani (CN7)
posterior 1/3: lingual + tonsillar branch (CN9)
epiglottis: pharyngeal branch (CN10)

Question 3

1st order neuron

Answer 3

pseudo unipolar cells in:
1.Geniculate ganglion CN7
2.Petrosal ganglion CN9
3.Nodose ganglion CN10
to solitary tract nucleus

Question 4

2nd order neuron

Answer 4

from solitary tract nucleus -> ascending solitariothalamic tract (central tegmental tract) -> VPM

Question 5

Collaterals

Answer 5

In central tegmental tract to:
Parabrachial nucleus of pons: to hypothalamus + amygdala -> limbic + autonomic
Cranial nerve secretomotor nuclei: salivation, tearing etc.

Question 6

3rd order neuron

Answer 6

from VPM via posterior limb of internal capsule to:
gustatory cortex of parietal operculum (Br.43) + parainsular cortex(projects to entorhinal cortex to hippocampa formation)

Question 7

Pharyngeal reflex / Gag reflex

Answer 7

Stimulus of the posterior tongue, soft palate, or posterior pharyngeal wall → sensory afferent nerve mainly via CN 9 (+CN 10 internal branch of superior laryngeal nerve) → brainstem → motor efferent nerve of CN 10 → causes bilateral pharyngeal muscle contraction