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The tympanic membrane (also tympanum or myrinx), is a thin membrane
Biological membrane

A biological membrane or biomembrane is an enclosing or separating amphipathic layer that acts as a barrier within or around a cell . It is, almost invariably, a lipid bilayer, composed of a double layer of lipid-class molecules, specifically phospholipids and cholesterol, with occasional integral membrane protein intertwined, some o...
 that separates the external ear from the middle ear
Middle ear

The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. The mammalian middle ear contains three ossicles, which couple vibration of the eardrum into waves in the fluid and membranes of the inner ear....
. Its function is to transmit sound
Sound

Sound is vibration transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a threshold of hearing to be heard, or the sensation stimulated in organs of hearing by such vibrations....
 from the air to the ossicles
Ossicles

Not to be confused with ossicones.The ossicles are the three smallest bones in the human body. They are contained within the middle ear space and serve to transmit sounds from the air to the fluid-filled labyrinth ....
 inside the middle ear. The malleus
Malleus

The malleus or hammer is a hammer-shaped small bone or ossicles of the middle ear which connects with the incus and is attached to the inner surface of the eardrum....
 bone bridges the gap between the eardrum and the other ossicles.

Rupture or perforation of the eardrum can lead to conductive hearing loss
Conductive hearing loss

Conductive hearing loss happens when there is a problem conducting sound waves through the outer ear, tympanic membrane or middle ear .This type of hearing loss may occur in conjunction with sensorineural hearing loss or alone....
.

Development
(In the picture to the right and up, the Malleus and Incus have been switched and the proper order is Malleus, Incus, then Stapes)The eardrum forms from the joining of the expanding first pharyngeal pouch
Pharyngeal pouch

In gastroenterology, a pharyngeal pouch is an uncommon pathological diverticulum of the pharyngeal mucosa through a weak area of the pharyngeal wall ....
 and groove
Pharyngeal groove

A pharyngeal groove is the counterpart of the branchial pouch on the ectodermal side.The first pharyngeal groove produces the ear canal. The rest produce no known structure in humans....
.






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The tympanic membrane (also tympanum or myrinx), is a thin membrane
Biological membrane

A biological membrane or biomembrane is an enclosing or separating amphipathic layer that acts as a barrier within or around a cell . It is, almost invariably, a lipid bilayer, composed of a double layer of lipid-class molecules, specifically phospholipids and cholesterol, with occasional integral membrane protein intertwined, some o...
 that separates the external ear from the middle ear
Middle ear

The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. The mammalian middle ear contains three ossicles, which couple vibration of the eardrum into waves in the fluid and membranes of the inner ear....
. Its function is to transmit sound
Sound

Sound is vibration transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a threshold of hearing to be heard, or the sensation stimulated in organs of hearing by such vibrations....
 from the air to the ossicles
Ossicles

Not to be confused with ossicones.The ossicles are the three smallest bones in the human body. They are contained within the middle ear space and serve to transmit sounds from the air to the fluid-filled labyrinth ....
 inside the middle ear. The malleus
Malleus

The malleus or hammer is a hammer-shaped small bone or ossicles of the middle ear which connects with the incus and is attached to the inner surface of the eardrum....
 bone bridges the gap between the eardrum and the other ossicles.

Rupture or perforation of the eardrum can lead to conductive hearing loss
Conductive hearing loss

Conductive hearing loss happens when there is a problem conducting sound waves through the outer ear, tympanic membrane or middle ear .This type of hearing loss may occur in conjunction with sensorineural hearing loss or alone....
.

Development


(In the picture to the right and up, the Malleus and Incus have been switched and the proper order is Malleus, Incus, then Stapes)The eardrum forms from the joining of the expanding first pharyngeal pouch
Pharyngeal pouch

In gastroenterology, a pharyngeal pouch is an uncommon pathological diverticulum of the pharyngeal mucosa through a weak area of the pharyngeal wall ....
 and groove
Pharyngeal groove

A pharyngeal groove is the counterpart of the branchial pouch on the ectodermal side.The first pharyngeal groove produces the ear canal. The rest produce no known structure in humans....
. Around day 30 of gestation
Gestation

Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during mammalian pregnancy can have one or more gestations at the same time ....
, the endoderm
Endoderm

Endoderm, is one of the germ layers formed during animal embryogenesis. Cells migrating inward along the archenteron from the inner layer of the gastrula, which develops into the endoderm....
-lined first expands to form the tympanic cavity
Tympanic cavity

The tympanic cavity is a small cavity surrounding the ossicles of the middle ear.It is formed from the tubotympanic sulcus, an expansion of the first branchial pouch....
, which subsequently envelops the inner ear ossicles
Ossicles

Not to be confused with ossicones.The ossicles are the three smallest bones in the human body. They are contained within the middle ear space and serve to transmit sounds from the air to the fluid-filled labyrinth ....
. Simultaneously, the first pharyngeal groove, which is lined with ectoderm, expands to form the developing external auditory meatus. Separated by a thin layer of splanchnic mesoderm, the tympanic cavity and external auditory meatus join to form the tympanic membrane. As a result, the tympanic membrane is one of very few adult structures that is derived from all three germ layer
Germ layer

A germ layer is a group of cell s, formed during animal embryogenesis. Germ layers are particularly pronounced in the vertebrates; however, all animals more complex than sea sponge produce two or three primary tissue layers ....
s. The skin that covers the outer surface of the tympanic membrane is derived from ectoderm
Ectoderm

The ectoderm is the start of a tissue that covers the body surfaces. It emerges first and forms from the outermost of the germ layers.Generally speaking, the ectoderm differentiates to form the nervous system, Epidermis , and the outer part of integumentary system....
, the fibrous tissue that forms the actual membrane is derived from mesoderm
Mesoderm

One of the three germ layers found in the embryos of animals more complex than cnidarians, making them triploblastic. Mesoderm forms in the embryo during gastrulation when some of the cells migrating inward to form the endoderm, produce an additional layer that lies between the endoderm and the ectoderm....
, and the mucus membrane that lines the inner surface of the membrane is derived from endoderm
Endoderm

Endoderm, is one of the germ layers formed during animal embryogenesis. Cells migrating inward along the archenteron from the inner layer of the gastrula, which develops into the endoderm....
.

Clinical Aspects

When examining the tympanic membrane with an otoscope
Otoscope

An Otoscope or auriscope is a medicine device which is used to look into the ears. Health care providers use otoscopes to screen for illness during regular check-ups and also to investigate when a symptom involves the ears....
, a bright cone of light is seen in the anterior-inferior part of the membrane. This light is known as the "cone of light" or "light reflex". The tympanic membrane is separated into four quadrants, with the center of the four quadrants being the umbo
Umbo of tympanic membrane

The umbo is the most depressed part of the tympanic membrane....
. Nerves, specifically the chorda tympani nerve, and arteries pass through the layers of the superior portion of the membrane. Thus, when the tympanic membrane needs to be incised for medical procedures, ENT surgeons will always cut through the inferior and posterior part of the membrane to avoid the vasculature, nerves, and bones associated with the membrane. The human body only contains one eardrum in each ear.

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