Biology of the Ears, Nose, and Throat | Merck Manual Consumer Version


The ears, nose, and throat have separate
but related functions. The throat is a passageway that carries food to the
esophagus and air to the lungs. At the entrance to the windpipe the voice box
contains vocal cords that open and close to produce the sound of the voice. This
is covered by a stiff flap of tissue called the epiglottis which prevents
food from entering the lungs. The ears are important for both hearing and
balance. The outer ear directs sound waves to the eardrum which vibrates against
tiny bones in the middle ear. This stimulates nerve cells in the inner
ear to generate nerve impulses that travel to the brain where they are
perceived as sound. Components of the inner ear called the vestibular system
gather information about the position and movement of the head to maintain
balance. The nose is the main passageway for air into and out of the lungs. The
nose warms, moistens, and cleans air and is also the organ of smell which is an
important component of taste. Finally, the sinuses are air-filled spaces
that open into the nasal cavity which reduce the weight of the facial bones
and skull while also maintaining shape.