![]() Unfortunately, it is also the auditory tubes that play a role in causing otitis media, as microorganisms can use this path to move from the pharynx into the middle ear. The auditory tube also provides a pathway of drainage for fluids that accumulate during middle ear infections ( otitis media). For this reason, chewing gum or drinking as the plane climbs will often relieve these symptoms. The auditory tube is normally closed, but will typically open when muscles of the pharynx contract during swallowing or yawning. If there is not a corresponding decrease in pressure in the middle ear, the pressure difference will cause the eardrum to push outward, causing pain and muffled hearing. As the plane climbs, pressure on the outside of the membrane decreases. When flying, you may have experienced what happens when the pressures across the tympanic membrane are not equal. The middle ear is also connected to the pharynx through the auditory tube (Eustachian tube) that helps equilize air pressure across the tympanic membrane. The stapes is then attached to the inner ear at the oval window where the sound waves will be transferred to the inner ear. The malleus is attached to the tympanic membrane and articulates with the incus, which articulates with the stapes. These small bones are the malleus, incus, and stapes, which are Latin names that roughly translate to hammer, anvil, and stirrup (Fig. The middle ear consists of a space spanned by three small bones, the ossicles, which amplify the movements of the tympanic membrane. ![]() Cerumen also helps prevent bacterial growth, waterproofs the auditory canal and tympanic membrane, and may be a deterrent to small insects. Because cerumen is sticky it can help prevent small particles from finding their way to the tympanic membrane. At the end of the auditory canal (sometimes caused external acoustic meatus) is the tympanic membrane, or ear drum, which vibrates with the movement of air in sound waves.Īlong the length of the auditory canal are ceruminous glands that contribute to the production of cerumen (earwax). The C-shaped curves of the auricle direct sound waves towards the ear canal, which enters into the skull through the external auditory meatus of the temporal bone. The outwardly visible structure that is often referred to as the ear is more correctly referred to as the outer ear (external ear), or the auricle. The ear is subdivided into 3 major parts: the external ear, middle ear, and internal ear. Hearing is the transduction of sound waves into a neural signal that relies on the structures of the ear. The brain uses this information to make any adjustments the body needs for balance.The ear is the organ of both hearing and equilibrium. This in turn changes the electrical impulses to the brain. Moving the head causes the fluid in the semi-circular canals to shift. The balance system works by sending continuous electrical impulses to the brain. The fluid wave stimulates the hair cells in the cochlea and an electrical impulse is sent through the eighth cranial nerve to the brain. A piston action of the ossicles creates a wave in the fluid in the inner ear. The ear drum vibrates which causes the ossicles (middle ear bones) to vibrate. The sound travels down the ear canal and hits the ear drum. The seventh cranial nerve is also known as the facial nerve because it supplies nerve impulses to the muscles of the face. ![]() Along with the eighth cranial nerve runs the seventh cranial nerve. This nerve carries both balance and hearing information to the brain. These semi-circular canals are filled with fluid and have some small calcium crystals embedded in the lining.Ĭoming from the inner ear and running to the brain is the eighth cranial nerve, the auditory nerve. This allows the brain to know in which direction the head is moving. These little canals are lined up at right angles (90°) to each other. The semi-circular canals are also known as the labyrinthine. The chambers are full of fluid which vibrates when sound comes in and causes the small hairs which line the membrane to vibrate and send electrical impulses to the brain. The cochlea is shaped like a snail and is divided into two chambers by a membrane. The cochlea, which is the hearing portion, and the semicircular canals is the balance portion. Next to the middle ear in the bone of the skull is a small compartment which contains the hearing and balance apparatus known as the inner ear.
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