27. TASTE PATHWAY
• Taste impulses from the anterior 2/3rd of the
tongue pass first into the lingual nerve
(Trigeminal nerve) - chorda tympani (facial
nerve) - tractus solitarius in the brain stem.
• Posterior 1/3rd of the tongue –
glossopharyngeal nerve - tractus solitarius
• Posterior most, pharynx – vagus nerve -
tractus solitarius
28.
29. Cont..
• Nucleus of the tractus solitarius (2nd order
neurons) (Medulla oblongata) - the nucleus of
the thalamus (3rd order neurons) - lower tip
of the postcentral gyrus in the parietal
cerebral cortex (Gustatory cortex)
30. Cont..
• These areas transmit signals to the
submandibular, sublingual, and parotid
glands to help control the secretion of saliva
during the ingestion and digestion of food.
31. Factors Influencing Taste Sensation
1. Temperature of substance - maximum
sensitivity to taste is obtained at 30 - 40
degree C
2. Olfaction – as it affects flavor
3. Individual variation - decrease in taste
sensitivity in older people due to atrophy of
taste buds
4. Sex - women are more sensitive to sweet and
salt and less sensitive to sour than men.
5. Adaptation - taste buds adapt quickly to a
particular taste
32. Taste Sensation Abnormalities
1. Ageusia- absence of taste sensation-
congenital or due to lesion of facial or
glossopharyngeal nerve.
2. Hypogeusia- diminished taste sensation due
to some diseases.
3. Dysgeusia- altered taste sensation.
33. PATHOLOGICAL TERMS
1. Tongue-tie - It is also known as ankyloglossia,
which is a condition in which a person's
tongue remains attached to the floor of their
mouth.
34. Cont..
2. Glossitis refers to inflammation of the
tongue. The condition causes the tongue to
swell and change color and texture.
35. Cont..
3. Macroglossia- It is an abnormal enlargement
of the tongue.
4. Atrophic glossitis- It is a condition in which
the tongue is missing some or all of its
papillae, making its usually rough surface
smooth.
36. Changes In Color Of Tongue
1. A bright pink color on the tongue is most
often due to a deficiency in iron, folic acid,
or vitamin B-12.
2. A white tongue is usually a result of smoking,
drinking alcohol, poor oral hygiene, or
candida infection.
37. Cont..
3. Leukoplakia and erythroplakia can cause
white or red patches on the tongue that can
be precursors to cancer.
