By-

V.Janarthanan.

The mouth cavity. The cheeks have been slit transversely and the tongue pulled forward.

View of tongue

Cut-away section of tongue to show three-dimensional view of papillae and underlying c.t. and muscle.

Close-up view of a tongue with visible fungiform papillae (large bumps) scattered among filiform papillae (small bumps).

Types of lingual papillae 1. Filiform papillae - These conical papillae are the most numerous.

Each consists of a long, slender core of connective tissue covered by epithelium. They are keratinized on their tips. They have no

tastebuds associated with them. 2. Fungiform papillae - Somewhat resemble a mushroom of the common edible variety. They are broad and round and non-cornified, with 1 - 5 tastebuds associated with them. Their epithelium overlies a

core of lamina propria. 3. Vallate (or circumvallate) papillae - are surrounded by a deep

furrow. Serous glands (von Ebner's glands) open into the bottom of the furrow and taste buds line the furrow. The"moat" around the circumvallate papilla is filled with secretions from these glands .

4. Foliate papillae - Well developed in some mammals (especially rabbits), foliate papillae are rudimentary in adult humans. They

contain many taste buds.

DISTRIBUTION OF VALLATE PAPILLAE

Circumvallate papilla in vertical section, showing arrangement of the taste-buds and

nerves

Circumvallate papilla

Section of tongue through circumvallate papilla. Notice glands immediately below it; also the interlacing skeletal muscle strands deeper in the section.

Detail of circumvallate papilla, showing pale taste buds opening into the lumen of the furrow that surrounds the papilla.

Section of a fungiform papilla. Magnified

A filiform papilla. Magnified.

Section of surface of tongue, showing one rather tangentially cut fungiform papilla at the left and some filiform papillae with sharp, semicornified tips at the

right. Cornification is less extensive in human tongue than in cats, dogs, etc.

Semidiagrammatic view of a portion of the mucous membrane of the tongue. Two fungiform papillae are shown. On some of the filiform papillae the epithelial

prolongations stand erect, in one they are spread out, and in three they are folded in.

 

Vertical section of papilla foliata of the rabbit, passing across the folia.

FOLIATE PAPILLAE

View of foliate papillae, typical of rabbit and some other animals. These have a characteristic 3-pronged connective tissue pattern extending up into the papilla,

and there are taste buds on the outside walls. Notice the bundles of skeletal muscle down below.

 

APPLIED The small bumps or nodules of tissue on your tongue are called papillae. Your

taste buds are scattered among these nodules. Sometimes, these papillae can become painful. Several papillae can hurt, or just one or two at a time.

Trauma is the most common cause of painful papillae of the tongue. The pain can occur because you have bitten your tongue or eaten something hot, such as pizza. Acidic foods such as orange juice and tomato sauce often can cause pain on traumatized areas of the tongue.

Some people unconsciously push the tips of their tongues against their upper teeth, which can cause tongue inflammation. People who grind or clench their teeth also irritate the edges of their tongues.

Benign migratory glossitis (also called geographic tongue is a condition of the tongue that can cause pain and can make your tongue more sensitive to spicy or acidic foods.

A painful tongue also can be a symptom of an underlying systemic (body-wide) condition, such as severe anemia, uncontrolled diabetes or a vitamin deficiency. Many skin diseases can affect the mouth. Yeast overgrowth and severe dry mouth (xerostomia) can lead to inflamed and painful papillae of the tongue.

Higher magnification of tongue surface, showing two filiform papillae. They are obviously extensions of stratified squamous epithelium.

Higher magnification of taste buds.

In humans, the sense of taste is conveyed via three of the twelve cranial nerves. The facial nerve (VII) carries taste sensations from the anterior two thirds of the tongue, the glossopharyngeal nerve (IX) carries taste sensations from the posterior one third of the tongue while a branch of the vagus nerve (X) carries some taste sensations from the back of the oral cavity.

In the lower buds note surface pores through which salivary fluids in the lumen of the furrow reach sensory nerve endings within the taste bud capsule. The cell bodies for these dendritic endings are pseudounipolar and lie within the sensory ganglion of a cranial nerve (such as Nerve VII).

The distribution of gustatory papillae

Drawing of a cross section through a taste bud from a foliate papilla

Impulse discharges in a single chorda tympani nerve

fiber of a rat.

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