Oral Mucosa: Tongue

Tongue Properties: Clinical Appearance

• Dorsal surface divided by the V-shaped sulcus terminalis into anterior two-thirds (body) and posterior one-third (base).

• The sulcus terminalis points to the foramen cecum.

• Dorsal surface has median lingual sulcus.

• Posterior one-third (pharyngeal part) forms tongue base, attaches to mouth floor, and is in the oral pharynx.

• Anterior two-thirds (body) lie within the oral cavity.

• Apex is the tongue tip.

• Lingual tonsil is on the base's dorsal surface.

• Ventral surface features visible deep lingual veins and plica fimbriata.

Tongue Examination

• Dorsal and lateral surfaces: extend tongue, grasp with gauze, palpate, and inspect.

• Ventral surface: lift tongue, inspect, and palpate.

Tongue Properties: Histologic Features

• Striated muscle covered by oral mucosa.

• Mobile anterior tongue has tight muscle bundles.

• Less mobile posterior tongue has minor salivary glands.

• Dorsal surface has masticatory and specialized mucosa.

• Masticatory mucosa is orthokeratinized stratified squamous epithelium.

• Specialized mucosa is associated with lingual papillae.

Lingual Papillae Properties: Introduction

• Fungiform, foliate, and circumvallate papillae have taste buds.

• Taste bud (TB) is epithelium-derived, barrel-shaped organ.

• Taste buds have 30-80 spindle-shaped cells.

• Turnover time is about 10 days.

• Two cell types: supporting cells (SC) and taste cells (TC).

• Taste pore (TP) is an opening at the surface.

• Supporting cells are on the outer part.

• Taste cells are central, with taste receptors.

• Dissolved food molecules contact taste receptors at the taste pore.

• Sensory neuron processes receive taste messages.

• Messages sent to CNS for taste identification.

• Factors affecting taste: aging, color impairments, hormones, genetics, temperature, drugs, CNS tumors, plugged noses.

• Four fundamental tastes: sweet, sour, salty, bitter.

• Tastes result from blending, tongue sensations, smell, and taste interplay.

• Taste maps are incorrect; all tastes can be elicited from all tongue regions with taste buds.

Lingual Papillae Types

• Four types: filiform, fungiform, foliate, and circumvallate.

• Filiform Papillae

  • Most common, on the body of the dorsal surface.

  • Fine-pointed cones, 2 to 3 mm long.

  • Give velvety texture.

  • Sensitive to body changes.

  • Pointed structure with keratinized epithelium.

  • Lack taste buds.

  • Clinical Considerations

  • Geographic Tongue: red and white patches that change shape.

  • Black Hairy Tongue: thick layer of dead cells and keratin.

  • Brushing reduces bad breath by reducing microbial colonization.

  • Hairy Leukoplakia: white lesion, associated with Epstein-Barr virus (EBV).

• Fungiform Lingual Papillae

  • Fewer than filiform papillae.

  • Reddish dots, mushroom-shaped, slightly raised, 1-mm diameter.

  • Not near sulcus terminalis.

  • Small mushroom shape with vascularized core.

  • Taste buds present.

  • Function is taste sensation.

• Foliate Lingual Papillae

  • 4 to 11 vertical ridges on the lateral surface.

  • Leaf-shaped structures.

  • Taste buds present.

  • Function is taste sensation.

• Circumvallate Lingual Papillae

  • Inverted V-shaped row on the dorsal surface.

  • Larger, 3 to 5 mm.

  • 7 to 15 large, raised structures.

  • Sunken with a circular trough.

  • Large mushroom shapes.

  • Hundreds of taste buds.

  • Function is taste sensation.

  • Von Ebner Salivary Glands Histologic Features

  • Von Ebner salivary glands (VE) are present in the submucosa deep to the lamina propria.

  • Only serous cells.

  • Ducts open into the trough.

  • Flush the area to introduce new taste sensations.

  • Function is taste.

Clinical Considerations for Tongue Pathology

• Fissured Tongue

  • Grooves on dorsal and lateral aspects.

  • Etiology unknown.

• Lingual Tonsil Lymphadenopathy:

  • Enlargement of the lingual tonsils.

• Tongue Piercing

  • Body of the tongue is the most common site.

  • Risk of infection.

• Oral Cancer of Tongue

  • Lateral border is common.

  • Initially asymptomatic.

  • Most commonly squamous cell carcinoma.