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Tongue

Lingua

For medical students2 min readUpdated 2026-10-10

The tongue is a muscular organ covered by a mucous membrane. Its core is formed by skeletal striated muscle tissue, whose fibers interlace in three mutually perpendicular directions, providing the organ with high mobility.

CoreSkeletal striated muscle tissue

Muscle architectureFibers run in 3 directions (longitudinal, transverse, vertical)

Types of papillaeFiliform, conical, fungiform, foliate, vallate

FunctionsMechanical, articulatory, sensory, secretory, protective

General Structural Plan

The tongue is not merely a muscle, but a complex structural system. Its anatomy comprises four main components:

Papillae (papillae): mucosal projections on the superior and lateral surfaces.
Salivary glands: embedded within the muscle mass, producing protein (serous), mucous, or mixed secretions.
Lymphoid tissue: forms the lingual tonsil at the root of the tongue (part of Waldeyer's ring).
Muscular core: provides mobility.

Histology of Tongue Surfaces

The structure of the mucous membrane directly depends on the surface.

Dorsal (Superior) Surface Characterized by the presence of papillae. The epithelium forms projections under which lies the lamina propria. A critical feature is the absence of a submucosa. Consequently, the mucosa fuses tightly with the underlying muscles (forming an aponeurosis) and is completely immobile.

Ventral (Inferior) Surface Smooth surface lacking papillae, covered by non-keratinized stratified squamous epithelium. Unlike the dorsal part, it features a well-developed submucosa containing large blood vessels, granting the mucosa slight mobility. Interestingly, the salivary glands on the ventral surface are not located in the submucosa, but deeper within the muscle mass.

Classification and Structure of Papillae

Every papilla consists of a primary papilla (a connective tissue projection of the lamina propria) and secondary papillae (smaller projections indenting the epithelium). Functionally, they are divided into two groups.

1. Mechanical (Filiform and Conical)

The smallest and most numerous.
Cover the tip and body of the tongue.
Their apices are covered by partially keratinized epithelium (the only papillae with this feature).
Give the tongue a velvety appearance and aid in the mechanical processing of food. Impaired desquamation of keratinized scales leads to a white coating ("coated tongue").

2. Gustatory (Taste Papillae) Covered by non-keratinized epithelium and contain taste buds.

Fungiform: narrow base and wide apex, scattered among filiform papillae on the tip and edges of the tongue.
Foliate: parallel folds on the lateral margins (4–8 on each side).
Vallate (Circumvallate): the largest, arranged in a V-shape at the boundary between the body and root. They do not project above the surface, surrounded by a trench and mucosal wall. Serous von Ebner glands empty into these trenches to flush out tastants.

Frequently asked questions

What cell types compose a taste bud?

A taste bud consists of several cell types, totaling 30–60 cells per bud. The cellular elements include:

Receptor (sensory) taste epithelial cells — dark, spindle-shaped nuclei with apical microvilli bearing specific protein receptors.
Supporting epithelial cells (sustentacular cells) — distinguished by round nuclei and often vacuolated cytoplasm.
Basal epithelial cells — located at the base of the taste bud.
Perigemmal (peripheral) cells — located at the periphery of the structure.

What are the histological features of the lingual tonsil?

Histologically, the lingual tonsil consists of mucosal folds containing aggregates of lymphoid tissue. It is located in the mucosa of the root of the tongue, posterior to the vallate papillae. Its lymphoid tissue is organized into two forms:

Lymphatic follicles — nodular aggregations.
Parafollicular aggregations — diffuse lymphoid tissue.

The tonsillar epithelium is infiltrated by immune cells, particularly granulocytes, lymphocytes, and macrophages.

Which nerves provide general sensory and gustatory innervation to the tongue papillae?

General sensation and taste are supplied by different cranial nerve branches depending on the region:

Anterior 2/3 of the tongue — general sensation by the lingual nerve (n. lingualis), and taste by the chorda tympani (chorda tympani).
Posterior 1/3 of the tongue and vallate papillae (papillae vallatae) — general and taste sensation by the glossopharyngeal nerve (n. glossopharyngeus).
Root of the tongue — innervated by the internal branch of the superior laryngeal nerve, a branch of the vagus nerve (n. vagus).

What is the main difference between the dorsal and ventral surfaces of the tongue?

The dorsal surface possesses papillae but lacks a submucosa (the mucosa is immobile). The ventral surface lacks papillae, has a smooth epithelium, and features a distinct submucosa (the mucosa is mobile).

Which tongue papillae undergo keratinization?

Only mechanical papillae—filiform and conical—feature partially keratinized epithelium.

Where are the glands on the ventral surface of the tongue located?

Despite the presence of a submucosa, salivary glands are absent there. They are located deeper, within the skeletal muscle tissue.

Go deeper

Histological structure of taste buds and the mechanism of taste perception.
Characteristics of von Ebner glands and their relationship with vallate papillae.
Structure of the lingual tonsil and its role in immune defense.
Differences between primary and secondary connective tissue papillae.