The Anatomy of Tongue And Perception of Taste

Creator: Dr. Sowmiya D
Published: 2022-05-06T12:54:36-04:00

Written by

Published on May 06, 2022 and last reviewed on Aug 01, 2023 - 4 min read

Abstract

The human tongue has essential functions ranging from bolus ingestion to chewing and swallowing. Read the article to learn about the tongue and its taste perception.

Contents

What Is the Function of Tongue?

What Are the Anatomy and Boundaries of the Tongue?

What Are the Different Surfaces of the Tongue?

What Are the Different Papillae of the Tongue?

What Are Taste Buds?

What Is the Function of Tongue?

Apart from chewing and deglutition, the tongue as a sensory organ is responsible for possessing the peripheral apparatus of taste buds and papillae for perceiving taste, facial expressions, and speech. In addition, the tongue makes the food bolus, and its movements also help in proper ingestion into the esophagus. On the other hand, the perception of taste is a complex process involving regulatory and peripheral inputs modulated by emotions and physiological and metabolic states, which are further enhanced by learning. Below we shall discuss the anatomy of the tongue and the papillae of the tongue containing taste buds in detail.

What Are the Anatomy and Boundaries of the Tongue?

The tongue is a muscular organ situated on the floor of the mouth; it comprises involuntary skeletal muscles. It is partly located in the oral cavity and partly in the pharynx.

The tongue is conical in shape and presents the following features:

The tip is the anterior end of the tongue, and these are in contact with the incisor teeth.
The posterior 1/3rd of the tongue forms the base.
The root is the part of the tongue attached to the floor of the mouth.
The lower fibers of the genioglossus connect it to the mandible and hyoid bone.
The two sides of the tongue are bordered by the free, lateral margins that come in contact with the teeth and gums.
These lateral margins, in turn, are merged with the palatoglossal fold. This union occurs at each side where the anterior 2/3rd meets the posterior 1/3rd.
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The tongue consists of two parts:

The oral part comprises the anterior 2/3rd.
The pharyngeal part is the posterior 1/3rd.

What Are the Different Surfaces of the Tongue?

The tongue has two surfaces, namely:

Dorsal surface.
Ventral surface.

1. Dorsal Surface: The dorsal surface is lined by non-keratinized stratified squamous epithelium. It is convex on all sides and divided into two parts by an inverted V-shaped sulcus called sulcus terminalis. The apex of the sulcus is directed backward. It is marked by a shallow depression called the foramen caecum, representing the site of the embryological origin of the thyroid gland.

There are two parts to the dorsal surface:

Presulcal or Oral Part - It constitutes the anterior 2/3rd of the dorsal surface and is placed on the floor of the mouth. The mucus membrane lining this part adheres to the underlying muscles by lamina propria. Numerous papillae of different types are present on this surface. They bear the taste buds. In addition, a median furrow representing the bilateral origin of the tongue is seen.
Post Sulcal or Pharyngeal Part - In this part, the mucus membrane overlies loose submucosa containing numerous mucus and serous glands. Additionally, many lymphoid follicles known as lingual tonsils are present. There are no papillae on this part.

2. Inferior or Ventral Surface:

The ventral or inferior surface of the tongue is lined by a thin mucus membrane which gets reflected onto the floor of the mouth. This surface is devoid of papillae, and it presents the following:

Frenulum linguae is a median fold of mucus membrane connecting the tongue to the floor of the mouth.
Lingual veins are seen under the mucus membrane, on either side of the frenulum.
The lingual nerve and artery lie medial to the veins on each side but are not visible.
Plica fimbriate consists of a fringe-like fold of mucus membrane present lateral to the lingual vein and are directed forwards and medially towards the tip of the tongue.
The sublingual papilla is present on each side of the base of the frenulum linguae as an elevation. It presents with the opening of the duct of the submandibular gland at its summit.

What Are the Different Papillae of the Tongue?

Papillae of the tongue are the surface projection of epithelium with a core of lamina propria. They are of four types:

Vallate Papillae: These are the largest, 1 to 2 mm, in diameter and 8 to 12 in number. They are situated in a single row adjacent to and in front of the sulcus terminalis. Each papilla is seen as a truncated conical projection surrounded by a circular sulcus at its base.
Fungiform Papillae: Numerous rounded reddish elevations present near the tip and margins of the tongue comprise the fungiform papillae.
Filiform Papillae: These are most numerous and cover most of the presulcal area of the dorsum of the tongue. They impart a velvety appearance to the tongue. In addition, filiform papillae provide the tongue with a rough surface to help grasp food.
Foliate Papillae: These kinds of papillae are present as 3 or 4 vertically arranged mucus folds on the lateral margin of the tongue, in front of sulcus terminalis.

What Are Taste Buds?

Taste buds, the primary sensory units of the taste system, are embedded under the tongue's papillae. The several types of taste cells in these papillae can be differentiated based on the presence or absence of dense granules. Recent research also shows that type 2 taste cells, particularly responsible for sweet sensation, even release ATP (adenosine triphosphate) due to tastant activation.

All papillae except filiform papillae contain taste buds. The taste buds are modified epithelial cells. The cells are arranged as spherical (barrel-shaped) masses of slender, spindle-shaped cells containing central gustatory cells surrounded by supporting cells. They converge apically and open on the tongue's surface by a gustatory pore. The afferent gustatory fibers penetrate the base of each bud.

Four taste sensations are projected onto the tongue:

Salt.
Sweet.
Sour.
Bitter.

Taste buds are present at the anterior 2/3 of the dorsum of the tongue, inferior surface of the soft palate, palatoglossal arches, posterior surface of the epiglottis, and rear wall of the oropharynx.

Conclusion:

To conclude, understanding the anatomy of the tongue and identification of taste receptors is essential for the physician to gain insight into the chemical, regulatory and physiologic functions in altered pathophysiologies.

Frequently Asked Questions

1. What Is the Physical Structure of Tongue and Taste Buds?

The tongue is a muscular organ in the mouth that helps taste, swallowing, and speech. It consists of specialized cells called papillae, which contain taste buds. Taste buds allow us to perceive the taste of drinks and food. Four papillae on the tongue are fungiform, filiform, foliate, and circumvallate. Filiform papillae do not contain taste buds. Circumvallate papillae are present on the back side of the tongue and contain many taste buds. Foliate taste buds decrease with age. Each taste bud comprises taste receptors, basal cells, and supporting cells. They provide particular taste sensations like sweet, sour, bitter, and salty.

2. What Are the Taste Perceptions?

Taste perception is the ability to detect different taste sensations like sweet, sour, salty, and bitter. It consists of several types of cells, like basal and sensory receptors. The molecules in the drink and food stimulate the taste receptors in the taste buds. The taste perception can be affected by health, age, and personal experience.

3. Which Nerve Helps for Taste?

The glossopharyngeal and facial nerve and its branches are responsible for taste perception. They carry the taste sensation from the back of the tongue and send it to the brain.

4. What Is the Physical Structure of Taste Receptors?

Taste receptors are present in the taste buds, which helps detect taste. It consists of several types of cells, like basal and supporting cells. Taste receptor cells are elongated cells known as microvilli. Supporting cells are present around the taste receptor cells. They protect the taste receptor cells from damage. Basal cells are present at the base of taste buds. It replaces the damaged receptor with a new one.

5. Which Part of the Tongue Helps in Identifying Sweetness?

The tip of the tongue is associated with sweetness. The sugar binds to the receptor cells and sends the signals to the brain, which detects the sweet taste sensation.

6. What Body System Controls the Tongue?

The nervous system controls the tongue. The 12 cranial nerves are responsible for controlling the taste sensation. The facial nerve controls the facial muscle and the anterior two-thirds of the tongue. The glossopharyngeal nerve controls the posterior one-third of the tongue.

7. What Body Organs Are Involved in Taste Perception?

Taste perception involves organs like the tongue, nervous system, taste buds, and brain.

8. What Are the Uses of Taste?

The uses are as follows:
- Taste perception.
- Speech and language.
- Chewing and swallowing.
- The tongue is coated with saliva, which helps in lubrication and cleaning the mouth.
- The tongue is sensitive to temperature, touch, and other sensations which detect changes in the environment.

9. Which Nerve Damage Leads to Loss of Taste?

The cranial nerve, including facial nerve and glossopharyngeal nerve damage, leads to loss of taste.

10. Which Tongue Part Is for Bitter Taste?

The back of the tongue is associated with a bitter taste. The glossopharyngeal nerve carries the taste sensation from the back of the tongue and sends it to the brain.

11. Which Tongue Part Is for Sour Taste?

The sides of the tongue are associated with a sour taste. The chorda tympani, a branch of the facial nerve, carries the taste signals from the side of the tongue and sends them to the brainstem.

12. Which Part of the Brain Control Taste?

The gustatory cortex is a part of the brain that controls taste. When the taste receptors detect taste, they send signals to the brain through the cranial nerves. The gustatory cortex interprets the taste sensations.