Tongue, histology, discussion, viva, oral, questions

1. What are the layers of tongue?
• Mucosa
• Partially keratinized stratified squamous epithelium
• Lamina propria
• Thick muscular layer
2. Why is epithelium rough on dorsal surface?
• The epithelium is rough on dorsal surface due to the projections called papillae
3. Name 4 types of papillae/ what are the 4 types of papillae?
• Filiform
• Fungiform
• Circumvallate
• Foliate
4. Which papillae is not seen in humans / which papillae is absent in humans?
• Foliate
5. Which papillae are more numerous?
• Filiform is more numerous covering entire anterior 2/3rd of dorsal surface of tongue
6. Which papillae is keratinized and which are non-keratinized?
• Filiform is keratinized
• Fungiform and circumvallate are non keratinized
7. What is the distribution of fungiform papillae?
• It is distributed at the tip and sides of tongue
8. What is the distribution of circumvallate papillae?
• Around 12 to 15 circumvallate papillae are present at the junction of anterior 2/3rd and posterior 1/3rd of the tongue
9. Describe filiform papillae
• Filiform papillae are bent sharp conical projections of epithelium directed posteriorly. It is partially covered by keratin at the tip
10. Describe fungiform papillae
• They are mushroom shaped larger, taller and broader papillae
• It has core of lamina propria surrounded by non-keratinized stratified squamous epithelium
• Few taste buds may be present towards surface of epithelium
11. Describe circumvallate papillae
• It is surrounded by deep trench or furrow. It is lined by non-keratinized stratified squamous epithelium with a core of lamina propria
• Lamina propria has numerous secondary papillae projecting into epithelium. It has connective tissue, blood vessels, nerves,  lymphatics and  von Ebner’s glands which open into trench
• Taste buds are present on lateral walls
12. Where are the taste buds present?
• They extend along the whole thickness of epithelium in lateral wall of circumvallate papillae and on surface epithelium of fungiform papillae
13. Describe taste buds
• Sustentacular cells or supporting cells- elongated with dark cytoplasm and slender dark nucleus
• Gustatory cells or taste cells or sensory cells or neuroepithelial cells-  lighter cytoplasm and oval light nucleus
• Basal cells near basement membrane of taste bud
• It has a small opening in the center which opens towards the epithelial surface
14. What are intragemmal and intergemmal fibers?
• Intragemmal fibers-  sensory fibers ending within the taste buds
• Intergemmal fibers-  fibers ending freely in epithelium in between taste cells
15. Name the components of lamina propria
• Loose connective tissue
• Blood vessels
• Nerves
• Lymphatics
16. What is the arrangement of muscular layer
• Muscular layer is very thick and fibers are arranged in various directions