NationMaster - Encyclopedia: Eustachian tube

The Eustachian tube (or auditory tube) is a tube that links the pharynx to the middle ear. In adults the Eustachian tube is approximately 35 mm long. It is named after the 16th century anatomist Eustachius.^[1] Some modern medical books call this the pharyngotympanic tube.^[2] human ear anatomy I made this myself Iain 05:39 29 Jun 2003 (UTC) version without labels File links The following pages link to this file: Ear Categories: GFDL images ... Image File history File links No higher resolution available. ... The malleus is 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 tensor tympani muscle arises from the auditory tube and inserts onto the handle of the malleus, damping down vibration in the ossicles and so reducing the amplitude of sounds. ... This article refers to a bone in the mammalian ear. ... The stapedius is the smallest striated muscle in the human body. ... For more uses of the word labyrinth, see Labyrinth (disambiguation) The labyrinth is a system of fluid passages in the inner ear, including both the cochlea which is part of the auditory system, and the vestibular system which provides the sense of balance. ... The stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the oval window which is adjacent to the vestibule of the inner ear. ... The ear canal (external auditory meatus, external acoustic meatus), is a tube running from the outer ear to the middle ear. ... The tympanum or tympanic membrane, colloquially known as eardrum, is a thin membrane that separates the outer ear from the middle ear. ... The tympanic cavity is a small cavity surrounding the bones of the inner ear. ... For other uses, see Latins and Latin (disambiguation). ... This article or section is in need of attention from an expert on the subject. ... Pharyngeal or branchial pouches form on the endodermal side between the branchial arches, and pharyngeal grooves (or clefts) form from the lateral ectodermal surface of the neck region to separate the arches. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Elseviers logo. ... The pharynx (plural: pharynges) is the part of the neck and throat situated immediately posterior to the mouth and nasal cavity, and cranial, or superior, to the esophagus, larynx, and trachea. ... The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. ... A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... (15th century - 16th century - 17th century - more centuries) As a means of recording the passage of time, the 16th century was that century which lasted from 1501 to 1600. ... Bartolomeo Eustachi (b. ...

Location

The Eustachian tube extends from the anterior wall of the middle ear to the lateral wall of the nasopharynx, approximately at the level of the inferior nasal concha. A portion of the tube (~1/3) proximal to the middle ear is made of bone; the rest is composed of cartilage^[3] and raises a tubal elevation, the torus tubarius, in the nasopharynx where it opens. The inferior nasal concha (Concha Nasalis Inferior; Inferior Turbinated Bone) extends horizontally along the lateral wall of the nasal cavity [Fig. ... The base of the cartilaginous portion of the Eustachian tube lies directly under the mucous membrane of the nasal part of the pharynx, where it forms an elevation, the torus tubarius or cushion, behind the pharyngeal orifice of the tube. ... The nasopharynx (nasal part of the pharynx) lies behind the nose and above the level of the soft palate: it differs from the oral and laryngeal parts of the pharynx in that its cavity always remains patent (open). ...

In the equids (horses) and some rodent-like species such as the desert hyrax, an evagination of the eustachian tube is known as the gutteral pouch and is divided into medial and lateral compartments by the stylohyoid bone of the hyoid apparatus. This is of great importance in equine medicine as the pouches are prone to infections, and due to their intimate relationship to the cranial nerves (VII,IX,X,XI) and the internal and external carotid artery, various syndromes may arise relating to which is damaged. Epistaxis (nosebleed) is a very common presentation to veterinary surgeons and this may often be fatal unless a balloon catheter can be placed in time to suppress bleeding.

Functions

Pressure equalization

Normally the Eustachian tube is closed, but it can open to let a small amount of air through to equalize the pressure between the middle ear and the atmosphere. When this happens we hear a small pop, an event familiar to aircraft passengers or drivers in mountainous regions. Yawning or swallowing can pull on muscles in the neck, causing the tube to open. Without this airway, air would be unable to escape from one's ear, the middle ear would be isolated from the atmosphere, and could be easily damaged by pressure changes. Image File history File links Emblem-important. ...

Some people are born with the ability to contract just these muscles voluntarily, similar to people who can wiggle their ears. Those who have this ability can hear a "popclickity" sound in the middle ear when actuating these muscles, and are able to hold the muscle contraction (some refer to this as 'clicking your ears to equalize the pressure').^{[citation needed]}Doing so will make one's voice sound louder to oneself. This ability allows such people to voluntarily equalize pressures at will when making rapid ascents or descents, typically in aircraft flights or large elevation changes in either tall buildings or mountainous treks. When the breath (inhale or exhale) is controlled, air pressure can be intentionally increased or decreased in the middle ear (breathing through the nose only or mouth), where the feeling of a cool air breeze can be felt inside the eustachian tube.

Occasionally, if the voluntary contraction timing is missed during a rapid pressure change, a slight yawning (opening of the jaw) action combines to assist in pressure equalization.

See also: Valsalva maneuver In medicine, the Valsalva maneuver is performed by forcibly exhaling against closed lips and pinched nose, forcing air into the middle ear if the Eustachian tube is open. ...

Mucus drainage

The Eustachian tube also drains mucus from the middle ear. Upper airway infections or allergies can cause the Eustachian tube to become swollen, trapping bacteria and causing ear infections. This swelling can be reduced through the use of pseudoephedrine. Earaches are more common in children because the tube is more horizontal and thinner, making the movement of fluid harder. Otitis media (also known as glue ear) is an inflammation of the middle ear, usually associated with a buildup of fluid. ... Pseudoephedrine (commonly abbreviated as PSE) is a sympathomimetic amine commonly used as a decongestant. ...

Embryologic development

The Eustachian tube is derived from the first pharyngeal pouch, which during embryogenesis forms a recess called the tubotympanic sulcus. The sulcus deepens to meet the first pharyngeal cleft forming the tympanic membrane. The distal part of the tubotympanic sulcus gives rise to the tympanic cavity, while the proximal tubular structure becomes the Eustachian tube. Embryogenesis is the process by which the embryo is formed and develops. ... In the development of vertebrate animals, the branchial arches (or pharyngeal arches) develop during the fourth and fifth week in utero as a series of mesodermal outpouchings on the left and right sides of the developing pharynx. ... The tympanum or tympanic membrane, colloquially known as eardrum, is a thin membrane that separates the outer ear from the middle ear. ... The tympanic cavity is a small cavity surrounding the bones of the inner ear. ...

Muscles

The Levator veli palatini is a muscle of the human body. ... The vagus nerve (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem (within the medulla oblongata) and extends, through the jugular foramen, down below the head, to the abdomen. ... The Salpingopharyngeus arises from the inferior part of the auditory tube near its orifice; it passes downward and blends with the posterior fasciculus of the Pharyngopalatinus. ... The tensor tympani muscle arises from the auditory tube and inserts onto the handle of the malleus, damping down vibration in the ossicles and so reducing the amplitude of sounds. ... The mandibular nerve is the third branch (V3) of the trigeminal nerve. ... The Tensor veli palatini muscle (or Tensor palati) is a muscle of the human body. ...

Disorders of the Eustachian tube

Some people are born with a dysfunctional Eustachian tube, which is much slimmer than the usual human Eustachian tube. This can either be genetic, or has been suggested to be a phenomenon occurring as a result of a hard birth, in which the baby's head was subject to an extraordinary amount of pressure, thus reshaping the Eustachian tube, making it much slimmer. The result of this disorder is a huge amount of mucus gathering in the middle ear, often impairing hearing to a degree. This condition is known as otitis media or glue ear. Otitis media is inflammation of the middle ear: the small space between the ear drum and the inner ear. ...

The disorder is treated by inserting small tubes (often known as grommets) through the tympanic membrane (ear drum). This allows any accumulation of mucus to flow directly out through the ear, as well as continually equalizing the pressure of the ear, throughout a subject's day. In some cases a person may be able to blow small amounts of air through the Eustachian tube and out through the ear, particularly if the Eustachian tubes are patulous (open).

Some people suffer from the rare patulous Eustachian tube condition, in which the Eustachian tube remains intermittently open, causing an echoing sound of their own heartbeat, breathing and speech, which may be temporarily relieved by flipping the head upside down. Patulous Eustachian tube is the name of a rare physical disorder where the Eustachian tube, which is normally closed, instead stays intermittently open. ...

Smoking can also cause damage to the cilia that protect the Eustachian tube from mucus which can result in the clogging of the tube and a buildup of bacteria in the ear leading to an inner ear infection in some cases. cross-section of two cilia, showing 9+2 structure A cilium (plural cilia) is a fine projection from a eukaryotic cell that constantly beats in one direction. ...

Eustachian tube dysfunction could be caused by recurring and chronic cases of sinus infection. This results from the excessive mucus production which causes obstruction to the openings of the eustachian tubes.

Additional images

References

Who Named It is a Norwegian database of several thousand eponymous medical signs and the doctors associated with their identification. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... The University Hospital The University of Michigan Health System is the medical unit of the University of Michigan in Ann Arbor. ...

External links

The human eye is the first element of a sensory system: in this case, vision, for the visual system. ... The auditory system is the sensory system for the sense of hearing. ... It has been suggested that Equilibrioception be merged into this article or section. ... The outer ear is the external portion of the ear. ... A left human ear. ... On the pinna, a curved prominence of cartilage, parallel with and in front of the helix, is called the antihelix, also known as the anthelix; this divides above into two crura, between which is a triangular depression, the fossa triangularis. ... In front of the concha, and projecting backward over the meatus, is a small pointed eminence, the tragus, so called from its being generally covered on its under surface with a tuft of hair, resembling a goatâ€™s beard. ... Opposite the tragus, and separated from it by the intertragic notch, is a small tubercle, the antitragus. ... On the ear of humans and many other animals, the earlobe (lobulus auriculÃ¦, sometimes simply lobe or lobule) is the soft lower part of the external ear or pinna. ... The ear canal (external auditory meatus, external acoustic meatus), is a tube running from the outer ear to the 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 tympanic membrane, colloquially known as the eardrum, is a thin membrane that separates the external ear from the middle ear. ... The umbo is the most depressed part of the tympanic membrane. ... The ossicles (also called auditory ossicles) are the three smallest bones in the human body. ... The malleus is 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. ... This article refers to a bone in the mammalian ear. ... The stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the oval window which is adjacent to the vestibule of the inner ear. ... The stapedius is the smallest striated muscle in the human body. ... The tensor tympani muscle arises from the auditory tube and inserts onto the handle of the malleus, damping down vibration in the ossicles and so reducing the amplitude of sounds. ... The base of the cartilaginous portion of the Eustachian tube lies directly under the mucous membrane of the nasal part of the pharynx, where it forms an elevation, the torus tubarius or cushion, behind the pharyngeal orifice of the tube. ... Inner ear The inner ear is the bony labyrinth, a system of passages comprising two main functional parts: the organ of hearing, or cochlea and the vestibular apparatus, the organ of balance that consists of three semicircular canals and the vestibule. ... For more uses of the word labyrinth, see Labyrinth (disambiguation) The labyrinth is a system of fluid passages in the inner ear, including both the cochlea which is part of the auditory system, and the vestibular system which provides the sense of balance. ... The bony labyrinth (osseous labyrinth) consists of three parts: vestibule semicircular canals cochlea These are cavities hollowed out of the substance of the bone, and lined by periosteum; they contain a clear fluid, the perilymph, in which the membranous labyrinth is situated. ... This is a page about the part of the ear. ... The membranous labyrinth is lodged within the bony labyrinth, and has the same general form; it is, however, considerably smaller, and is partly separated from the bony walls by a quantity of fluid, the perilymph. ... The helicotrema is the part of the cochlear labyrinth where the scala tympani and the scala vestibuli meet. ... The round window is one of two membranes that separates the inner ear from the middle ear. ... The cochlea is the auditory portion of the inner ear. ... The spiral ganglion is the group of nerve cells that serve the sense of hearing by sending a representation of sound from the cochlea to the brain. ... The modiolus is a conical shaped central axis in the cochlea. ... The cochlear duct (or scala media) is an endolymph filled cavity inside the cochlea, located in between the scala tympani and the scala vestibuli, separated by the basilar membrane and Reissners membrane (the vestibular membrane) respectively. ... Endolymph is the fluid contained in the membranous labyrinth of the inner ear. ... The upper portion of the spiral ligament contains numerous capillary loops and small blood vessels, and is termed the stria vascularis. ... The periosteum, forming the outer wall of the ductus cochlearis, is greatly thickened and altered in character, and is called the spiral ligament. ... The organ of Corti is the organ in the inner ear of mammals that contains auditory sensory cells, or hair cells. // Structure and function It has highly specialized structures that respond to fluid-borne vibrations in the cochlea with a shearing vector in the hairs of some cochlear hair cells. ... Scala vestibuli is a perilymph filled cavity inside the cochlea of the inner ear. ... Scala tympani is the name of one of the perilymph filled cavities in the cochlear labyrinth. ... Perilymph is a fluid located within the cochlea (part of the ear) in 2 of its 3 muscles; the scala typmani and scala vestibuli. ... Reissners membrane is a membrane inside the cochlea of the inner ear, it separates scala media from scala vestbuli and together with the basilar membrane it creates a compartment in the cochlea filled with perilymph, which is important for the function of the organ of Corti inside the scala... Cross section of the cochlea. ... Covering the sulcus spiralis internus and the spiral organ of Corti is the tectorial membrane, which is attached to the limbus laminae spiralis close to the inner edge of the vestibular membrane. ... The organ of Corti is the organ in the inner ear of mammals that contains auditory sensory cells, or hair cells. // Structure and function It has highly specialized structures that respond to fluid-borne vibrations in the cochlea with a shearing vector in the hairs of some cochlear hair cells. ... Hair cells are the sensory cells of both the auditory system and the vestibular system in all vertebrates. ... Section through the spiral organ of Corti. ... The basilar crest gives attachment to the outer edge of the basilar membrane; immediately above the crest is a concavity, the sulcus spiralis externus. ... On the upper plate of that part of the lamina which is outside the vestibular membrane, the periosteum is thickened to form the limbus laminÃ¦ spiralis, this ends externally in a concavity, the sulcus spiralis internus, which represents, on section, the form of the letter C. Histology at uc. ... The osseous spiral lamina consists of two plates of bone, and between these are the canals for the transmission of the filaments of the acoustic nerve. ... It has been suggested that Equilibrioception be merged into this article or section. ... The utricle, larger than the saccule, is of an oblong form, compressed transversely, and occupies the upper and back part of the vestibule, lying in contact with the recessus ellipticus and the part below it. ... The portion of the utricle which is lodged in the recess forms a sort of pouch or cul-de-sac, the floor and anterior wall of which are thickened, and form the macula of utricle, which receives the utricular filaments of the acoustic nerve. ... Categories: Stub ... The saccule is the smaller of the two vestibular sacs; it is globular in form, and lies in the recessus sphÃ¦ricus near the opening of the scala vestibuli of the cochlea. ... From the posterior wall of the saccule a canal, the ductus endolymphaticus, is given off; this duct is joined by the ductus utriculosaccularis, and then passes along the aquaeductus vestibuli and ends in a blind pouch, the endolymphatic sac, on the posterior surface of the petrous portion of the temporal... From the posterior wall of the saccule a canal, the endolymphatic duct, is given off; this duct is joined by the ductus utriculosaccularis, and then passes along the aquaeductus vestibuli and ends in a blind pouch (saccus endolymphaticus) on the posterior surface of the petrous portion of the temporal bone... A kinocilium is a special structure connected to the hair cells of the inner ears cochlea. ... An otolith, (oto-, ear + lithos, a stone), also called statoconium[1] or otoconium is a structure in the saccule or utricle of the inner ear, specifically in the vestibular labyrinth. ... inner ear illustration showing semicircular canal, hair cells, ampulla, cupula, vestibular nerve, & fluid The semicircular canals are three half-circular, interconnected tubes located inside each ear that are the equivalent of three gyroscopes located in three planes perpendicular (at right angles) to each other. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The posterior semicircular canal, vertical like the superior, is directed backward, nearly parallel to the posterior surface of the petrous bone; it is the longest of the three canals, measuring from 18 to 22 mm. ... The lateral or horizontal canal (external semicircular canal) is the shortest of the three canals. ... The cupula forms the apex of the cochlea. ... The bony semicircular canals are three in number, superior, posterior, and lateral, and are situated above and behind the vestibule. ... This article does not cite any references or sources. ... Human brain In animals, the brain (enkephale) (Greek for in the skull), is the control center of the central nervous system, responsible for behavior. ... The Cochlear nerve (n. ... The vestibulocochlear nerve (also known as the auditory or acoustic nerve) is the eighth of twelve cranial nerves, and is responsible for transmitting sound and equilibrium (balance) information from the inner ear to the brain. ... The cochlear nuclei consist of: (a) the dorsal cochlear nucleus, corresponding to the tuberculum acusticum on the dorso-lateral surface of the inferior peduncle; and (b) the ventral or accessory cochlear nucleus, placed between the two divisions of the nerve, on the ventral aspect of the inferior peduncle. ... The trapezoid body is part of the acoustic pathway. ... For the cerebellar structure, see Dentate nucleus. ... The lateral lemniscus is a tract of axons in the brainstem that carries information about sound from the cochlear nucleus to various brainstem nuclei and ultimately the contralateral inferior colliculus of the midbrain. ... The paired inferior colliculi together with the superior colliculi form the eminences of the corpora quadrigemina. ... The medial geniculate nucleus is a nucleus of the thalamus that acts as a relay for auditory information. ... The primary auditory cortex is the region of the brain that is responsible for processing of auditory (sound) information. ...

Contents

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