mouth but guarding the oral cavity against the
ingestion of excessively hot or cold substances. They
also provide a seal for the mouth to keep food and
saliva from escaping. The lips help to maintain the
position of the teeth and are very important in speech.
The tongue (fig. 3-18) is a vascular, thick solid
mass of voluntary muscle surrounded by a mucous
membrane (epithelium tissue). Located on the
underneath side of the tongue is the lingual frenulum,
which anchors the tongue in the midline to the floor of
the mouth. The tip of the tongue is free moving and can
readily change size, shape, and position.
Surface (Dorsal Aspect)
On the surface of the tongue are rough projections
called papillae. They provide the tongue with friction
in handling food and also act as taste buds.
The four types of taste sensations are sweet, sour,
bitter, and salty-all resulting from stimulation of the
taste buds. Most are located on the tongue and the roof
of the mouth. Figure 3-19 illustrates taste buds of the
Figure 3-19.Taste buds of the tongue.
Tongue and Digestion
The tongue is an important muscle in the chewing
process. It crushes food against the palate; it deposits
food between the chewing surfaces of the teeth for
Figure 3-18.Dorsal aspect of tongue (left), anatomy floor of mouth (right).