iPedia Free Information Center

Information about Eardrum

Eardrum
Anatomy of the human ear.
Right tympanic membrane as seen through a speculum.
Latinmembrana tympani
subject #230 1039


The tympanic membrane, colloquially known as the eardrum, is a thin membrane that separates the external ear from the middle ear. Its function is to transmit sound vibrations from the air, conducted through the external acoustic meatus to the ossicles inside the middle ear. The malleus bone bridges the gap between the eardrum and the other ossicles.

Arterial supply - outer surface is supplied by the deep auricular branch of the maxillary artery,inner surface is supplied by the anterior tympanic branch of the maxillary artery & by the posterior tympanic branch of the stylomastoid branch of the posterior auricular artery. Venous drainage - outer surface drains into the external jugular vein.inner surface drains into the transverse sinus & into the venous plexus around the auditory tube.

Lymphatic drainage – pass to the preauricular & retropharyngeal nodes. Nerve supply – Outer surface – anteroinferior part is supplied by the auriculotemporal nerve & the posterosuperior part by the auricular branch of the vagus nerve. Inner surface is supplied by the tympanic branch of the glossopharyngeal nerve through the tympanic plexus.

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

Development

The eardrum forms from the joining of the expanding first pharyngeal pouch and groove. Around day 30 of gestation, the endoderm-lined first expands to form the tympanic cavity, which subsequently envelops the inner ear ossicles. 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 layers. The skin that covers the outer surface of the tympanic membrane is derived from ectoderm, the fibrous tissue that forms the actual membrane is derived from mesoderm, and the mucus membrane that lines the inner surface of the membrane is derived from endoderm.

Clinical Aspects

When examining the tympanic membrane with an otoscope, 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. 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.

Additional images


External and middle ear, opened from the front. Right side.

Horizontal section through left ear; upper half of section.

The right membrana tympani with the hammer and the chorda tympani, viewed from within, from behind, and from above.

Auditory tube, laid open by a cut in its long axis.

Chain of ossicles and their ligaments, seen from the front in a vertical, transverse section of the tympanum.


External links

 •  • [ e]
Sensory system: Auditory and Vestibular systems
Outer earPinna (Helix, Antihelix, Tragus, Antitragus, Earlobe) • Ear canal
Middle earEardrum • Ossicles (Malleus, Incus & Stapes) • Stapedius • Tensor tympani • Eustachian tube (Torus tubarius)
Inner ear/LabyrinthBony labyrinth (Vestibule) • Membranous labyrinth
Oval window • Helicotrema • Round window
Cochlea: Spiral ganglion • Modiolus • Cochlear duct/scala media (Endolymph, Stria vascularis, Spiral ligament, Organ of Corti) • Scala vestibuli and Scala tympani (Perilymph)
Reissner's/vestibular membrane • Basilar membrane • Tectorial membrane
Organ of Corti: Hair cells • Stereocilia • Sulcus spiralis (externus, internus) • Limbus spiralis
Vestibular systemStatic/translations: Utricle (Macula) - Saccule (Macula, Endolymphatic sac, Endolymphatic duct) - Kinocilium - Otolith
Kinetic/rotations: Semicircular canals (Superior, Posterior, Horizontal) • Cupula • Ampullae (Crista ampullaris)
Brain (auditory)Cochlear nerve VIII → Cochlear nuclei → Superior olivary nuclei → Lateral lemniscus → Inferior colliculi → Medial geniculate nuclei → Primary auditory cortex
Latin}}} 
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
..... Click the link for more information.
See also:
A biological membrane or biomembrane is an enclosing or separating tissue which acts as a barrier within or around a cell.
..... Click the link for more information.
The outer ear is the external portion of the ear.

Pinna, or auricle

The visible part is called the pinna and functions to collect and focus sound waves. Many mammals can move the pinna (with the auriculares muscles) in order to focus their hearing in a certain direction
..... Click the link for more information.
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.
..... Click the link for more information.
Sound is a disturbance of mechanical energy that propagates through matter as a wave (through fluids as a compression wave, and through solids as both compression and shear waves).
..... Click the link for more information.
The ossicles (also called auditory 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 (cochlea).
..... Click the link for more information.
malleus or hammer is a hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum. The word is Latin for hammer.
..... Click the link for more information.
Perforated eardrum
Classification & external resources

ICD-10 H 72.
ICD-9 384.2

DiseasesDB 13473

eMedicine ent/206  

MeSH C09.218.903 Rupture or perforation (hole) of the eardrum can occur in infection, trauma (e.g.
..... Click the link for more information.
MeSH D006314 Conductive hearing loss is a failure in the efficient conduction of sound waves through the outer ear, tympanic membrane (eardrum) or middle ears (ossicles). This type of hearing loss may occur in conjunction with sensorineural hearing loss or alone.
..... Click the link for more information.
pharyngeal pouch is a pathological pulsion diverticulum of the pharyngeal mucosa through Killian's dehiscence. Killian's dehiscence (also known as Killian's triangle) is a triangular area in the wall of the pharynx between the inferior constrictor muscle and the cricopharyngeus
..... Click the link for more information.
In the development of vertebrate animals, the pharyngeal arches (also called branchial arches or gill arches in fish) develop during the fourth and fifth week in utero
..... Click the link for more information.
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time (multiple gestations).
..... Click the link for more information.
Endoderm is one of the germ layers formed during animal embryogenesis. Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm.

The endoderm consists at first of flattened cells, which subsequently become columnar.
..... Click the link for more information.
The tympanic cavity is a small cavity surrounding the bones of the middle ear.

It is formed from the tubotympanic sulcus, an expansion of the first pharyngeal pouch.
..... Click the link for more information.
The ossicles (also called auditory 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 (cochlea).
..... Click the link for more information.
The ear canal (external auditory meatus, external acoustic meatus), is a tube running from the outer ear to the middle ear. The ear canal extends from the pinna to the eardrum and is about 26 mm in length and 7 mm in diameter.
..... Click the link for more information.
Lateral plate mesoderm (or hypomere) is a type of mesoderm that is found at the periphery of the embryo.

Division into layers

It will split into two layers, the somatic layer/mesoderm and the splanchnic layer/mesoderm
  • The somatic layer

..... Click the link for more information.
germ layer is a collection of cells, formed during animal embryogenesis. Germ layers are only really pronounced in the vertebrates. However, all animals more complex than sponges (eumetazoans and ) produce two or three primary tissue layers
..... Click the link for more information.
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.

What forms from it (general)?

  • Nervous system
  • Outer part of integument

What forms from it (vertebrates)?


..... Click the link for more information.
The germ layer mesoderm forms in the embryos of animals more complex than cnidarians, making them triploblastic. Mesoderm forms during gastrulation when some of the cells migrating inward to form the endoderm form an additional layer between the endoderm and the ectoderm.
..... Click the link for more information.
Endoderm is one of the germ layers formed during animal embryogenesis. Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm.

The endoderm consists at first of flattened cells, which subsequently become columnar.
..... Click the link for more information.
An Otoscope or auriscope is a medical 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.
..... Click the link for more information.
umbo.

External links

  • Diagram
  • Diagram
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated.
..... Click the link for more information.
The chorda tympani is a nerve that branches from the facial nerve (cranial nerve VII) inside the facial canal, just before the facial nerve exits the skull via the stylomastoid foramen.
..... Click the link for more information.
sensory system: in this case, vision, for the visual system. ]]

A sensory system is a part of the nervous system responsible for processing sensory information.
..... Click the link for more information.
The auditory system is the sensory system for the sense of hearing.

Ear

Main article: Ear

Outer ear

Main article: Outer ear

..... Click the link for more information.
The vestibular system, or balance system, is the sensory system that provides the dominant input about our movement and orientation in space. Together with the cochlea, the auditory organ, it is situated in the vestibulum in the inner ear (Figure 1).
..... Click the link for more information.
The outer ear is the external portion of the ear.

Pinna, or auricle

The visible part is called the pinna and functions to collect and focus sound waves. Many mammals can move the pinna (with the auriculares muscles) in order to focus their hearing in a certain direction
..... Click the link for more information.
The pinna (Latin for feather) is the visible part of the ear that resides outside of the head (this may also be referred to as the auricle or auricula).

Purpose

The purpose of the pinna is to collect sound.
..... Click the link for more information.
The prominent rim of the auricula is called the helix. Where the helix turns downward behind, a small tubercle is frequently seen: the auricular tubercle of Darwin.

Additional images



The muscles of the auricula.

..... Click the link for more information.


This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.
Herod_Archelaus


page counter