Tympanic Membrane

What is Tympanic Membrane?

Tympanic membrane is also known as eardrum. It is a structure that makes up the middle ear. It is characterized by a thin cone-shaped membrane of pearly gray in color and is translucent. Eardrum can be found lying at the end of the external auditory canal and marks the lateral limits of the middle ear.

Picture 1:

image source: hearinghealthmatters.org

The edge of tympanic membrane is attached to tympanic annulus that almost encircles and holds the membrane in place. The upper portion where the ring is open is called the pars flaccid which receive no tension. Pars tensa is the majority of the membrane that is tightly stretched.

Tympanic Membrane Functions

1. Tympanic membrane physiologically functions to conduction of sound. It receives sound from the external air and transmits it to the auditory ossicles.
2. Tympanic membrane also acts as a shield from direct sound waves and also protects the mucosa of the middle ear from factors of the external environment.
3. Sound vibrations coming from the outer air is received by tympanic membrane and transmits them to the tiny bones, called auditory ossicles, in the tympanic cavity.

Tympanic Membrane Innervations

Tympanic membrane composed the middle ear or the tympanic cavity. This tympanic cavity is laterally compressed space inside the temporal bone. It is filled with air where it passes through the nasal part of the pharynx going to the auditory tube.

Tympanic cavity also consists of tiny chain of bones which are movable and is connected to the medial wall which is responsible in conveying vibrations to the tympanic membrane across the cavity to the internal ear.

picture 2: Tympanic cavity which is just located behind the tympanic memberane.

image source: i.vimeocdn.com

The arteries of the tympanic membrane originated from the deep auricular branch of the maxillary, stylomastoid branch of the posterior auricular, and from the tympanic branch of the internal maxillary. The ectodermal or outer surface is supplied with nerve by the auriculotemporal branch of the trigeminal nerve and by the auricular branch of the vagus nerve.

Nerve supplying the eardrum also supplies the external auditory meatus. Superficial veins of the membrane are open to the external jugular while those in the deep surface drains partly into the transverse sinus and veins of the dura mater and some part drains into the plexus on the auditory tube.

 

Tympanic Membrane Rupture/Perforation

Tympanic membrane rupture or perforation is a condition of the middle ear characterized by a hole that is usually due to increased pressure stretching the eardrum to the limits. Pain is the most common symptom of a perforated ear however, when the eardrum ruptures, the pain decreases and mucopurulent discharge with blood appears in the external auditory canal.

Perforated eardrum heals on its own usually 2 weeks after the eardrum ruptured. Inflammatory process gradually regresses and restoration preceded by tympanic membrane healing and normal hearing is restored.

picture 3: Perforated eardrum

image source: sydneyentclinic.com

A hole or tear in the tympanic membrane can result to a hearing loss or various form of infection that when left untreated may lead to a more serious complication. Although tympanic membrane heals on its own within a week, there are case in which the perforation persists or do not heal for several months. Those that do not heal may require surgical intervention and while in the process of healing, it is important that infection may be prevented.

Pain is the most common symptom ranging from general discomfort to severe. There may be a consistent pain which may stop suddenly. Drainage of fluid from the external auditory canal may be observed and the fluid may be filled with blood and pus. The infection will cause the tympanic cavity to swell creating pressure greater than the pressure in the external auditory canal.

The increase in pressure will stress the tympanic membrane resulting in tight stretch until it reaches its maximum and rupture. Ringing in the ears or buzzing sound may be experience including bouts of dizzy spells or vertigo. Nausea and vomiting may also be experience due to onset of vertigo.

Infection is the most common cause of ruptured eardrum. Otitis media or middle ear infection will result to fluid accumulation and lead to pressure build up that can later on rupture the eardrum. Imbalance in the air pressure of the middle ear and the environment will stress the eardrum and cause it to rupture. This stress due to pressure imbalance is referred to as barotrauma.

Infection is not the only cause for ruptured eardrum, injury to the middle ear will also cause it to rupture. Injury may be in the form of direct slap to the ear or may be due traumas involving the head. Other form of injury to the tympanic membrane may also include foreign object being pushed into the middle ear.

The goal of treating perforated tympanic membrane is pain alleviation and prevention of infection which may lead to a more serious complication. The condition must be given medical attention as this may also result to impaired hearing or loss of hearing. Hearing loss is common in tympanic membrane rupture although it is temporary and resumes when the rupture is healed.

It is also very important to keep the ear dry to prevent further infection and give tympanic membrane some time to heal.