In the

anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...

of humans and various other

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct t ...

s, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped

membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. ...

that separates the

external ear The outer ear, external ear, or auris externa is the external part of the ear, which consists of the auricle (also pinna) and the ear canal. It gathers sound energy and focuses it on the eardrum (tympanic membrane). Structure Auricle The ...

from the

middle ear The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear). The mammalian middle ear contains three ossicles, which transfer the vibrations of the eardrum into waves in the ...

. Its function is to transmit

sound In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' b ...

from the air to the ossicles inside the middle ear, and then to the

oval window The oval window (or ''fenestra vestibuli'' or ''fenestra ovalis'') is a membrane-covered opening from the middle ear to the cochlea of the inner ear. Vibrations that contact the tympanic membrane travel through the three ossicles and into the in ...

in the fluid-filled

cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the Organ of Corti, the sensory or ...

. Hence, it ultimately converts and amplifies vibration in the air to vibration in cochlear fluid. The

malleus The malleus, or hammer, is a hammer-shaped small bone or ossicle of the middle ear. It connects with the incus, and is attached to the inner surface of the eardrum. The word is Latin for 'hammer' or 'mallet'. It transmits the sound vibrations f ...

bone bridges the gap between the eardrum and the other ossicles. Rupture or

perforation of the eardrum A perforated eardrum (tympanic membrane perforation) is a hole in the eardrum. It can be caused by infection (otitis media), trauma, overpressure (loud noise), inappropriate ear clearing, and changes in middle ear pressure. An otoscope can be u ...

can lead to

conductive hearing loss Conductive hearing loss (CHL) occurs when there is a problem transferring sound waves anywhere along the pathway through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles). If a conductive hearing loss occurs in conjunction with ...

. Collapse or retraction of the eardrum can cause conductive hearing loss or

cholesteatoma Cholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process. Cholesteatomas are not cancerous as the name may suggest, but can cause significant problems because of th ...

Structure

Orientation and relations

The tympanic membrane is oriented obliquely in the

anteroposterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

, mediolateral, and superoinferior planes. Consequently, its superoposterior end lies lateral to its anteroinferior end. Anatomically, it relates superiorly to the

middle cranial fossa The middle cranial fossa, deeper than the anterior cranial fossa, is narrow medially and widens laterally to the sides of the skull. It is separated from the posterior fossa by the clivus and the petrous crest. It is bounded in front by the pos ...

, posteriorly to the

ossicle The ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ...

s and

facial nerve The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste ...

, inferiorly to the

parotid gland The parotid gland is a major salivary gland in many animals. In humans, the two parotid glands are present on either side of the mouth and in front of both ears. They are the largest of the salivary glands. Each parotid is wrapped around the ma ...

, and anteriorly to the

temporomandibular joint In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that it ...

Regions

The eardrum is divided into two general regions: the

pars flaccida In human anatomy, the pars flaccida of tympanic membrane or Shrapnell's membrane (also known as Rivinus' ligament) is the small, triangular, flaccid portion of the tympanic membrane, or eardrum. It lies above the malleolar folds attached directl ...

and the

pars tensa In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air ...

. The relatively fragile pars flaccida lies above the lateral

process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management *Business process, activities that produce a specific se ...

of the

between the

notch of Rivinus {{Technical, date=November 2013 The Notch of Rivinus is a small defect in the posterior edge of the bony annular tympanic ring. The defect is located just superior to the tympano-mastoid suture line in the posterior ear canal The ear canal (ex ...

and the anterior and posterior malleal folds. Consisting of two layers and appearing slightly pinkish in hue, it is associated with Eustachian tube dysfunction and

s. The larger pars tensa consists of three layers:

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...

fibrous tissue Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...

, and mucosa. Its thick periphery forms a fibrocartilaginous ring called the

annulus tympanicus Annulus (or anulus) or annular indicates a ring- or donut-shaped area or structure. It may refer to: Human anatomy * ''Anulus fibrosus disci intervertebralis'', spinal structure * Annulus of Zinn, a.k.a. annular tendon or ''anulus tendineus com ...

or Gerlach's ligament. while the central umbo tents inward at the level of the tip of malleus. The middle fibrous layer, containing radial, circular, and parabolic fibers, encloses the handle of malleus. Though comparatively robust, the pars tensa is the region more commonly associated with perforations.

Umbo

The manubrium ( la, handle) of the

is firmly attached to the medial surface of the membrane as far as its center, drawing it toward the

tympanic cavity The tympanic cavity is a small cavity surrounding the bones of the middle ear. Within it sit the ossicles, three small bones that transmit vibrations used in the detection of sound. Structure On its lateral surface, it abuts the external auditory ...

. The lateral surface of the membrane is thus concave. The most depressed aspect of this concavity is termed the umbo ( la,

shield boss A shield boss, or umbo, is a round, convex or conical piece of material at the centre of a shield. Shield bosses (or sometimes, just "bosses") are usually made of thick metal but could also be made of wood. The boss was originally designed to de ...

Nerve supply

Sensation of the outer surface of the tympanic membrane is supplied mainly by the

auriculotemporal nerve The auriculotemporal nerve is a branch of the mandibular nerve (CN V3) that runs with the superficial temporal artery and vein, and provides sensory innervation to various regions on the side of the head. Structure Origin The auriculotempor ...

, a branch of the mandibular nerve ( cranial nerve V₃), with contributions from the

auricular branch of the vagus nerve The auricular branch of the vagus nerve is often termed the Alderman's nerve or Arnold's nerve. The latter name is an eponym for Friedrich Arnold. The auricular branch of the vagus nerve supplies sensory innervation to the skin of the ear canal, t ...

(

cranial nerve X The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right v ...

), the

(cranial nerve VII), and possibly the

glossopharyngeal nerve The glossopharyngeal nerve (), also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper medulla, just anterior (closer to the nose) to the vagus nerve. ...

(cranial nerve IX). The inner surface of the tympanic membrane is innervated by the glossopharyngeal nerve.

Clinical significance

Examination

When the eardrum is illuminated during a

medical examination In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the patie ...

, a cone of light radiates from the tip of the malleus to the periphery in the anteroinferior quadrant, this is what is known clinically as 5 o'clock.

Rupture

Unintentional

perforation A perforation is a small hole in a thin material or web. There is usually more than one perforation in an organized fashion, where all of the holes collectively are called a ''perforation''. The process of creating perforations is called perfor ...

(rupture) has been described in blast injuries and

air travel Air travel is a form of travel in vehicles such as airplanes, jet aircraft, helicopters, hot air balloons, blimps, gliders, hang gliders, parachutes, or anything else that can sustain flight.

, typically in patients experiencing

upper respiratory The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa. Air is breathed in through the nose to t ...

congestion that prevents equalization of pressure in the middle ear. It is also known to occur in

swimming Swimming is the self-propulsion of a person through water, or other liquid, usually for recreation, sport, exercise, or survival. Locomotion is achieved through coordinated movement of the limbs and the body to achieve hydrodynamic thrust that r ...

diving Diving most often refers to: * Diving (sport), the sport of jumping into deep water * Underwater diving, human activity underwater for recreational or occupational purposes Diving or Dive may also refer to: Sports * Dive (American football), a ...

(including

scuba diving Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface air supply. The name "scuba", an acronym for " Self-Contained Underwater Breathing Apparatus", was coined by Chr ...

), and martial arts. Patients with tympanic membrane rupture may experience bleeding,

tinnitus Tinnitus is the perception of sound when no corresponding external sound is present. Nearly everyone experiences a faint "normal tinnitus" in a completely quiet room; but it is of concern only if it is bothersome, interferes with normal hearin ...

hearing loss Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spoken ...

, or disequilibrium (

vertigo Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...

). However, they rarely require medical intervention, as between 80 and 95 percent of ruptures recover completely within two to four weeks. The prognosis becomes more guarded as the force of injury increases.

Surgical puncture for treatment of middle ear infections

The pressure of fluid in an infected middle ear onto the eardrum may cause it to rupture. Usually, this consists of a small hole (perforation), which allows fluid to drain out. If this does not occur naturally, a

myringotomy A myringotomy is a surgical procedure in which an incision is created in the eardrum (tympanic membrane) to relieve pressure caused by excessive buildup of fluid, or to drain pus from the middle ear. A tympanostomy tube may be inserted through th ...

(tympanotomy, tympanostomy) can be performed. A myringotomy is a

surgical Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...

procedure in which a tiny incision is created in the eardrum to relieve pressure caused by excessive buildup of fluid, or to drain

pus Pus is an exudate, typically white-yellow, yellow, or yellow-brown, formed at the site of inflammation during bacterial or fungal infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection ...

from the

. The fluid or pus comes from a middle ear infection (

otitis media Otitis media is a group of inflammatory diseases of the middle ear. One of the two main types is acute otitis media (AOM), an infection of rapid onset that usually presents with ear pain. In young children this may result in pulling at the ear, ...

), which is a common problem in children. A

tympanostomy tube Tympanostomy tube, also known as a grommet or myringotomy tube, is a small tube inserted into the eardrum in order to keep the middle ear aerated for a prolonged period of time, and to prevent the accumulation of fluid in the middle ear. The ope ...

is inserted into the eardrum to keep the middle ear aerated for a prolonged time and to prevent reaccumulation of fluid. Without the insertion of a tube, the incision usually heals spontaneously in two to three weeks. Depending on the type, the tube is either naturally extruded in 6 to 12 months or removed during a minor procedure. Those requiring myringotomy usually have an obstructed or dysfunctional eustachian tube that is unable to perform drainage or ventilation in its usual fashion. Before the invention of antibiotics, myringotomy without tube placement was also used as a major treatment of severe acute otitis media. In some cases, the pressure of fluid in an infected middle ear is great enough to cause the eardrum to rupture naturally. Usually, this consists of a small hole (perforation), from which fluid can drain.

Society and culture

The

Bajau The Sama-Bajau include several Austronesian ethnic groups of Maritime Southeast Asia. The name collectively refers to related people who usually call themselves the Sama or Samah (formally A'a Sama, "Sama people"); or are known by the exonym ...

people of the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

intentionally rupture their eardrums at an early age to facilitate diving and hunting at sea. Many older Bajau therefore have difficulties hearing.

Additional images

File:Anatomy of the Human Ear en.svg, Anatomy of the human right ear. File:Gray907.png, External and middle ear, right side, opened from the front (coronal section) File:Gray908.png, Horizontal section through left ear; upper half of section File:Gray912.png, The right membrana tympani with the hammer and the chorda tympani, viewed from within, from behind, and from above File:Gray915.png, Auditory tube, laid open by a cut in its long axis File:Gray919.png, Chain of ossicles and their ligaments, seen from the front in a vertical, transverse section of the tympanum ympanic cavityFile:Gray909.png, Right eardrum as seen through a speculum File:Normal Left Tympanic Membrane.jpg, This is a normal left eardrum. File:Tympanic membrane viewed by otoscope.png, Tympanic membrane viewed by otoscope File:Traumatic Perforation of the Tympanic Membrane.jpg, The oval perforation in this left tympanic membrane was the result of a slap on the ear File:Subtotal Perforation of the right tympanic membrane.tif, A subtotal perforation of the right tympanic membrane resulting from a previous severe otitis media File:TM RIGHT NORMAL.jpg, A normal human right tympanic membrane (eardrum) File:Frog on leaf with eardrum.jpg, Frog on leaf showing eardrum

References

External links

Diagram at Georgia State University

{{Authority control Auditory system Ear