The throat (pharynx) is located behind the mouth, below the nasal cavity, and above the hollow tube that leads from the throat to the stomach (esophagus) and windpipe (trachea) (see figure A Look Inside the Nose and Throat). It consists of an upper part (nasopharynx), a middle part (oropharynx), and a lower part (hypopharynx). The throat is a muscular passageway through which food is carried to the esophagus and air is carried to the lungs. Like the nose and mouth, the throat is lined with a mucous membrane composed of cells that produce mucus and have hairlike projections (cilia). Dirt particles caught in the mucus are carried by the cilia toward the esophagus and are swallowed.
The tonsils are small lumps of tissue located on both sides of the back of the mouth, and the adenoids are located at the back of the nasal cavity. The tonsils and adenoids consist of lymphoid tissue and help fight off infections (see also Lymphatic System: Helping Defend Against Infection). They are largest during childhood and gradually shrink throughout life. Even when the tonsils and adenoids are removed surgically, because of obstructive sleep apnea (when breathing is temporarily blocked during sleep) or repeated infections (adenotonsillitis), the body can still fight off infections because the rest of the immune system is still available to fight infection.
The uvula is a small flap of tissue visible in the back of the throat between the tonsils. It varies in length. As part of the soft palate, the uvula helps prevent food and fluids from entering the nasal cavity during swallowing and assists in the formation of certain sounds during speech. A long uvula may cause snoring and occasionally contributes to obstructive sleep apnea.
At the top of the trachea is the voice box (larynx), which contains the vocal cords and is primarily responsible for producing the sound of the voice. When relaxed, the vocal cords form a V-shaped opening that air can pass through freely. When contracted, they vibrate as air from the lungs passes over them, generating sounds that can be modified by the tongue, nose, and mouth to produce speech.
The epiglottis is a stiff flap of cartilage located above and in front of the larynx. During swallowing, the epiglottis covers the opening to the larynx to prevent food and fluids from entering the trachea. Thus, the epiglottis protects the lungs.