Throat

The throat (pharynx) is located behind the mouth, below the nasal cavity, and above the esophagus and windpipe (trachea). 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 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 located on both sides of the back of the mouth, and the adenoids at the back of the nasal cavity. The tonsils and adenoids consist of lymphoid tissue and help fight off infections. They are largest during childhood and gradually shrink throughout life. The uvula is a small flap of tissue visible in the back of the throat between the tonsils. It helps prevent food and fluids from entering the nasal cavity during swallowing.

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.