The mouth or oral cavity is formed by the lips, cheeks, hard and soft palates, uvula, and the tongue and its muscles (Fig. 14-1).

Contained within the mouth are the tongue, teeth, gums, and openings of the salivary glands (parotid, submandibular, and sublingual). The gums (gingiva) are covered by mucous membrane and normally hold 32 permanent teeth in the adult (Fig. 14-2).

Three pairs of salivary glands secrete saliva (watery, serous fluid containing salts, mucus, and salivary amylase) into the mouth (Fig. 14-3): the parotid glands, the submandibular glands, and the sublingual glands.

The throat (pharynx), located behind the mouth and nose, serves as a muscular passage for food and air (see Fig. 14-4). The upper part of the throat is the nasopharynx. Below the nasopharynx lies the oropharynx, and below the oropharynx lies the laryngopharynx.

The nose is composed of bone and cartilage covered with skin and an internal nasal cavity, lined with mucous membrane. The external nose consists of a bridge (upper portion), tip, and two oval openings called nares. The nasal cavity (Fig. 14-4) is located between the roof of the mouth and the cranium separated into halves by the nasal septum. The front of the nasal septum contains Kiesselbach area, a rich supply of blood vessels.

The superior, middle, and inferior turbinates (conchae) are bony lobes that project from the nasal cavity, increasing the surface area that is exposed to incoming air (see Fig. 14-4). As the person inspires air, nasal hairs (vibrissae) filter large particles from the air. Ciliated mucosal cells then capture and propel debris toward the throat, where it is swallowed. A meatus underlies each turbinate and receives drainage from the paranasal sinuses and the nasolacrimal duct.

Four pairs of paranasal sinuses (frontal, maxillary, ethmoidal, and sphenoidal) are located in the skull. The paranasal sinuses are lined with ciliated mucous membrane that traps debris and propels it toward the outside. The frontal sinuses (above the eyes) and the maxillary sinuses (in the upper jaw) are accessible to the examiner, whereas the ethmoidal and sphenoidal sinuses are smaller, located deeper in the skull, and not accessible for direct examination.