- tion is easily remedied. Nosebleed, though generally unimportant,
may be serious in adults.
The Mouth.—The mouth is of great importance as an entrance for fresh air to the lungs when the nasal passages are for any reason impeded and as the resonant chamber from which proceeds the voice, man's chief means of communication with his fellows. Its chief value may be said, however, to reside in the fact that it is the vestibule of the alimentary canal. It is an ovoid cavity lined with mucous membrane and is bounded in front by the lips, at the sides by the cheeks, below by the floor and tongue, and above by the hard palate anteriorly and by the soft palate posteriorly, the uvula depending from the latter like a curtain between the mouth and the pharynx. Shape is given to the mouth by the bones of the upper and lower jaw and its size is altered by the lowering and raising of the latter, which is quite freely movable.
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Fig. 19.—The hyoid bone. (Toldt.)
At the back of the mouth, at the entrance to the pharynx, are the anterior and posterior pillars of the fauces, which contain muscular tissue, and between which on either side are thick masses of lymphoid tissue, the tonsils. The floor of the mouth is formed largely by the tongue, which completely fills the space within the lower teeth.
