Ear, Nose, and Throat

Transcript

Dr. Connolly
The ears, nose, and throat are responsible for some fundamental functions that not only keep the body healthy, but also make life enjoyable. Dr. Alvarado, can you tell us about the ears, nose, and throat?

Dr. Alvarado
Definitely, Dr. Connolly. Obviously, the ears make it possible for us to hear, and they also help us maintain our balance. The ear is made up of three different sections: the outer ear, the middle ear, and the inner ear.

The outer ear is the part of the ear that's visible on the side of your head. This part is also called the pinna or auricle. The pinna gathers sound waves and funnels them to the ear canal, a hollow passage that leads to the eardrum, or tympanic membrane. Glands in the skin lining the ear canal produce earwax, which protects the canal from dirt and infections.

The eardrum separates the outer ear from the middle ear, an air-filled cavity about the size of a pea. The middle ear has three small bones, called ossicles, that transmit the incoming sound waves to the inner ear. The names of the ossicles are the malleus, incus, and stapes.

In order to hear properly, the pressure on either side of the eardrum must be equal. A canal that links the middle ear with the back of the nose, called the eustachian tube, helps equalize the pressure in the middle ear.

The inner ear consists of the cochlea, the vestibule, and the semicircular canals. The snail-shaped cochlea converts the incoming sound waves into nerve impulses that travel to the brain through the cochlear nerve, or auditory nerve. The vestibule and semicircular canals are organs that help us maintain our equilibrium, or balance. They send messages to the brain through the vestibular nerve.

The nose is the organ responsible for smell, and it's where air enters the body when we inhale. Odors and oxygen enter the nose through the nostrils, which are separated by a wall of cartilage called the nasal septum. Nasal hairs at the opening of the nostrils trap large particles that could cause illness or irritation.

Smaller particles, such as pollen or smoke, are trapped by mucus secreted by a mucous membrane that lines the inside of the nose. Hairlike structures called cilia move these particles out of the nose.

From the nose, inhaled air enters the nasal cavity. The receptors of the nerve responsible for our sense of smell, called the olfactory nerve, are located within the mucous membrane of the nasal cavity.

The nasal cavity is surrounded by the air-filled chambers called paranasal sinuses. These sinuses are named for the bones in which they are located: frontal, maxillae, ethmoid, and sphenoid.

The throat is a muscular, funnel-shaped tube that acts as a passageway for air, food, and liquid. The throat contains the tonsils and adenoids, which release white blood cells that fight infection.