Tongue

The tongue is a multifunctional organ mostly involved in eating and speech.

Function of the tongue

• Eating: the tongue is located in the mouth and is the first organ to come into contact with foods. The papillae the upper surface of the tongue allow us to taste and analyse the food. The papillae recognise at least four types of flavour: sweet, salt, acid and bitter. The tongue can detect whether foods are appropriate to be eaten (bitterness is often a sign of contamination or poison). It is also needed to masticate and swallow foods and has many powerful muscles to do so.
• Speech: the tongue is the speech organ. Sounds produced differ according to its place in the mouth its shape and interaction with the lips or teeth.

Structure of the tongue

The tongue is a mobile soft highly muscled organ approximately 10 centimetres long which can be divided into three parts:

• the buccal segment (opened when the mouth is open);
• the pharyngeal segment (at the back of the throat);
• and the root of the tongue (fixed to the hyoid bone).

The tongue has 7 intrinsic muscles (three pairs plus one) and 8 extrinsic muscles (four pairs) which makes it highly mobile. It is very highly vascularised particularly on the inferior surface where the lingual artery arrives. The tongue also has extensive innervation: these are sensory (taste), sensory (mechanical sensations, heat and cold), and motor (for mobility).

The papillae are only located on the anterior surface of the tongue. There are four types of these:

• the circumvallate (or caliciform) papillae located at the back of the tongue;
• the fungiform papillae which are arranged throughout the tongue;
• the filiform papillae which are present in larger numbers
• the foliate papillae (or corolliform) papillae which are located on the sides of the tongue.