Tongue

From ArticleWorld

The tongue is the major organ of the mouth and is a muscular structure anchored to the floor of the mouth. It carries the multiple functions of aiding in chewing, articulating speech and in tasting ingested substances.

Anatomy

The muscles that attach the tongue to the floor of the mouth are called its extrinsic muscles. These are also the muscles that allow one to protrude the tongue from the mouth and bring it back into the mouth.

Intrinsic muscles are those within the body of the tongue itself. There are four pairs of longitudinal muscles that generally work together. These are the muscles that allow the tongue to form different shapes such as when an individual rolls his or her tongue. All of these muscles are skeletal muscle, meaning that they are under voluntary control.

The tongue has two distinct surfaces. The underside of the tongue has a smooth mucous membrane surface and does not participate in the taste process. The dorsum or upper surface of the tongue is rough due to the presence of bumpy papillae that project from the tongue outward. There are four types of papillae on the tongue: the filiform papillae, the fungiform papillae, foliate papillae and vallate papillae. All but the filiform papillae contain taste buds. Near the pharynx, at the base of the tongue, are slightly larger bumps known as the lingual tonsil. This part of the tongue is part of the lymphatic or lymph system.

Physiology

As mentioned, there are three primary functions involving the tongue. The extrinsic and intrinsic muscles of the tongue participate in the articulation of speech. Many alphabetical sounds are made with the tongue placed in a certain position. The most common positions involve placing the tip of the tongue onto the hard palate and the placing of the tip of the tongue between the lips or on the front teeth.

Chewing or masticating would be difficult without the intrinsic tongue muscles. The tongue helps move food in boluses toward the teeth where the food can be further broken down. The tongue can also smash food between itself and the hard palate. In addition, the tongue is used along with other parts of the mouth to determine that food has been sufficiently broken into pieces small enough for swallowing.

The tongue’s papillae have, on their surfaces, taste buds that provide the sensation known as taste. Contrary to popular belief, there are no areas of the tongue that are specific to one taste and all taste buds have the capacity to respond to the different types of tastes.

There are four different tastes that can be sensed. They are the sensation of salt, bitterness, sweetness and savoriness (also known as Umami). The last taste sensation has only recently been identified. The taste sensation of “savory” is difficult to describe. Many describe it as a taste similar to that of a common mushroom.