About the Ears, Nose, and Throat

Understanding the parts of the ear, nose, and throat will help you talk with your doctor about any symptoms you may have or treatments you may need.

What are the Ears?

The ear is the organ of hearing and balance. Sound waves enter the outer ear, travel down the external auditory canal, and strike the eardrum (tympanic membrane), which vibrates. The vibrations are passed to three tiny bones in the middle ear called the ossicles, which amplify the sound and send the sound waves to the inner ear and into the hearing organ (cochlea). Once the sound waves reach the inner ear, they are converted into electrical impulses, which the auditory nerve sends to the brain. The brain then translates these electrical impulses into sound.

The parts of the ear include the following structures:

The external ear, or outer ear, consists of the following:

• Pinna or auricle: This is the outer part of the ear.
• External auditory canal or tube: This tube connects the outer ear to the inside or middle ear.
• Tympanic membrane (also called the eardrum): This membrane divides the external ear from the middle ear.

The middle ear, or tympanic cavity, consists of the following:

• Ossicles: These are three tiny bones—called malleus, incus, and stapes—that transmit sound waves to the inner ear.
• Eustachian tube: This canal links the middle ear with the back of the nose. The eustachian tube helps to equalize pressure in the middle ear, which is needed for the proper transfer of sound waves. The eustachian tube is lined with mucous, just like the inside of the nose and throat.

The inner ear consists of the following:

• Cochlea: This structure contains the nerves for hearing.
• Vestibule: This has receptors for balance.
• Semicircular canals: These contain receptors for balance.

What is the Nose?

The nose is the organ of smell and is part of the peripheral nervous system. The internal part of the nose lies above the roof of the mouth. The nose consists of the following:

• External nose: A triangular-shaped projection in the center of the face.
• Nostrils: These are two chambers divided by the septum.
• Septum: This is made up primarily of cartilage and bone and covered by mucous membranes. The cartilage also gives shape and support to the outer part of the nose.
• Nasal passages: Passages lined with mucous membranes and tiny hairs (cilia) that help filter the air.
• Sinuses: Four pairs of air-filled cavities that are also lined with mucous membranes.

What are the Sinuses?

The sinuses are cavities near the nasal passage lined with mucous membranes. There are four types of sinuses:

• Ethmoid sinus: Located inside the face, around the bridge of the nose. It is present at birth and continues to grow.
• Maxillary sinus: Located inside the face, around the cheeks. It is also present at birth and continues to grow.
• Frontal sinus: Located inside the face, in the forehead area. It does not develop until around seven years of age.
• Sphenoid sinus: Located deep in the face, behind the nose. It does not typically develop until adolescence.

What is the Throat?

The throat is a ring-like muscular tube that acts as the passageway for air, food, and liquid. The throat also helps in forming speech. The throat consists of:

• Larynx (also known as the voice box): The larynx is a cylindrical structure of cartilage, muscles, and soft tissue that contains the vocal cords. The vocal cords are the upper opening into the windpipe (trachea), the passageway to the lungs.

• Epiglottis: A flap of soft tissue located just above the vocal cords. The epiglottis folds down over the vocal cords to prevent food and irritants from entering the lungs.

• Tonsils and adenoids: These are made up of lymph tissue and are located at the back and sides of the mouth. They protect against infection but generally have little purpose beyond childhood.