Histology of the Tongue

A comprehensive set of practice flashcards covering tongue histology, including tissue layers, epithelium, papillae types, taste buds, glands, and taste distribution.

What are the three main layers of the tongue and their basic components?

Mucosa (surface epithelium), Submucosa (connective tissue with blood vessels), and Muscularis (skeletal muscle fibers in various directions).

What type of epithelium lines the dorsal and ventral surfaces of the tongue, and how does keratinization differ between them?

Dorsal surface epithelium over papillae is partially keratinized (parakeratinised); ventral surface has non-keratinized stratified squamous epithelium. Some areas of the dorsum are keratinized where papillae are present (filiform tips).

What is the sulcus terminalis and what boundary does it define on the tongue?

A V-shaped groove on the dorsal tongue; apex points backwards and marks the boundary between the anterior oral part (2/3) and the posterior pharyngeal part (1/3).

Where is the foramen caecum located and what is its significance?

At the apex of the sulcus terminalis on the dorsum of the tongue. It marks the end of the V-shaped sulcus and corresponds to embryonic thyroid origin. (In notes, it is described as an apex depression.)

How is the tongue divided anatomically into its anterior and posterior parts?

By the sulcus terminalis into a larger anterior oral part (2/3) and a smaller posterior/pharyngeal part (1/3).

Name the four main types of lingual papillae.

Filiform, Fungiform, Circumvallate, and Foliate (foliate).

Which lingual papillae are the most numerous on the tongue?

Filiform papillae.

Which papillae are mushroom-shaped and contain taste buds?

Fungiform papillae.

Describe circumvallate papillae and their location.

Largest papillae arranged in a row just anterior to the sulcus terminalis; each has a circular top within a groove; taste buds are on the lateral and inner walls; serous glands of Von Ebner are nearby.

What glands are associated with circumvallate papillae and what is their proposed function?

Serous glands of Von Ebner; secrete fluid to dissolve tastants and wash them over taste buds.

What is papilla simplex and how does it differ from other papillae?

A microscopic papilla type consisting of projections of connective tissue into the epithelium, not surface projections; distinct from the other visible papillae.

What are taste buds and where are they located in relation to papillae?

Taste buds are piriform structures within the epithelium containing gustatory receptor cells, supporting cells, and basal cells; they open to the surface via a gustatory pore and are located on circumvallate, fungiform, and foliate papillae (also present in soft palate, epiglottis, palatoglossal arches, and posterior pharynx).

What cells comprise a taste bud and what are their roles?

Gustatory (receptor) cells detect tastants and have afferent nerve endings; sustentacular (supporting) cells provide support; basal cells serve as progenitors.

What is the role of von Ebner’s serous glands in relation to taste buds?

Dissolve tastants and spread them over taste buds, aiding taste perception and washing substances away after tasting.

Where are the anterior lingual glands located and what do they contain?

Largest glands on the ventral aspect of the tongue apex; contain both mucous and serous acini.

What is the distribution of taste buds beyond the major papillae?

Taste buds are also present on leaf-like folds of mucosa (folia linguae) on the posterolateral part of the tongue, and on the soft palate, epiglottis, palatoglossal arches, and posterior pharynx.

Which areas on the tongue are most strongly associated with sweet, salty, and bitter tastes?

Sweet tastes are best at the tip of the tongue; salty tastes just behind the tip and along the lateral border; bitter tastes are associated with circumvallate papillae.

What is the muscular makeup of the tongue and its functional significance?

The tongue contains intrinsic and extrinsic skeletal muscles arranged in vertical, transverse, and longitudinal directions, enabling wide-ranging movements for chewing, swallowing, and speech.

What is the epithelium like on the tips of filiform papillae?

The tips are keratinized, giving a rough surface.

What is the epithelium of the ventral tongue surface like?

Non-keratinized stratified squamous epithelium.

What are foliate papillae and where are they located?

Leaf-like folds along the posterolateral tongue that contain taste buds.

What is the arrangement and role of taste buds within the epithelium?

Taste buds extend through the thickness of the epithelium and have a gustatory pore on the surface; they house receptor and supporting cells with central nuclei and nerve endings nearby.

What is the gross anatomy feature termed the ‘apex’ of the sulcus terminalis?

The apex points backward toward the pharynx; the foramen caecum marks this apex.