ossicula auditus

耳小骨

関

ear ossicle

WordNet

1. a methodical examination or review of a condition or situation; "he made an audit of all the plants on his property"; "an energy efficiency audit"; "an email log audit"
2. attend academic courses without getting credit
3. examine carefully for accuracy with the intent of verification; "audit accounts and tax returns" (同)scrutinize, scrutinise, inspect

PrepTutorEJDIC

1. 会計検査(監査) / 決算報告[書] / …‘の'会計検査(監査)をする / 《米》(大学の講義)'を'聴講する / 会計検査(監査)をする

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/02 08:40:22」(JST)

wiki en

[Wiki en表示]

This article is about the bones in the human ear. For elements embedded in the body wall of echinoderms, see Ossicle (echinoderm).

Ossicles
Auditory ossicles: Malleus, incus and stapes
Details
Latin	Ossicula auditus, ossicula auditoria
Identifiers
Gray's	p.1044
MeSH	A09.246.397.247
Dorlands /Elsevier	Ossicles
TA	A02.1.17.001
FMA	52750
Anatomical terms of bone

This article is one of a series documenting the anatomy of the
Human ear
Outer ear Pinna Tragus
Middle ear Tympanic membrane Ossicles Malleus Incus Stapes
Inner ear Vestibules Utricle Saccule Cochlea Semicircular canals
See also Development of the ears Anatomical terminology

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 ossicles would constitute a moderate-to-severe hearing loss. The term "ossicle" literally means "tiny bone" and, though the term may refer to any small bone throughout the body, it typically refers to the malleus, the incus and the stapes of the middle ear.

Structure

See also: Malleus, Incus and Stapes

Anatomy of the three ossicles.

The ossicles are, in order from the eardrum to the inner ear (from superficial to deep): the malleus, incus, and stapes, terms that in Latin are translated as "the hammer, anvil, and stirrup".

• The malleus (Latin: "hammer") articulates with the incus through the incudomalleolar joint and is attached to the tympanic membrane (eardrum), from which vibrational sound pressure motion is passed.
• The incus (Latin: "anvil") is connected to both the other bones.
• The stapes (Latin: "stirrup") articulates with the incus through the incudostapedial joint and is attached to the membrane of the fenestra ovalis, the elliptical or oval window or opening between the middle ear and the vestibule of the inner ear. It is the smallest bone in the body.

Development

Studies have shown that ear bones in mammal embryos are attached to the dentary, which is part of the jaw. These are ossified portions of cartilage—called Meckel's cartilage—that are attached to the jaw. As the embryo develops, the cartilage hardens to form bone. Later in development, the bone structure breaks loose from the jaw and migrates to the inner ear area. The structure is known as the middle ear, and is made up of the stapes, incus, malleus, and tympanic membrane. These correspond to the columella, quadrate, articular, and angular structures in the amphibian, bird or reptile jaw. For this reason, researchers believe that mammals and reptiles share a common ancestry.

Evolution

Main article: Evolution of mammalian auditory ossicles

Function

As sound waves vibrate the tympanic membrane (eardrum), it in turn moves the nearest ossicle, the malleus, to which it is attached. The malleus then transmits the vibrations, via the incus, to the stapes, and so ultimately to the membrane of the fenestra ovalis, the opening to the vestibule of the inner ear.

Sound traveling through the air is mostly reflected when it comes into contact with a liquid medium; only about 1/30 of the sound energy moving through the air would be transferred into the liquid. Think about the abrupt cessation of sound that occurs on a busy summer's day at the pool when you submerge your head underwater. This is because the relative incompressibility of a liquid presents resistance to the force of the sound waves traveling through the air. The ossicles give the eardrum a mechanical advantage via lever action and a reduction in the area of force distribution; the resulting vibrations would be much weaker if the sound waves were transmitted directly from the outer ear to the oval window. This reduction in the area of force application allows a large enough increase in pressure to transfer most of the sound energy into the liquid. The increased pressure will compress the fluid found in the cochlea and transmit the stimulus. Thus, the presence of the ossicles to concentrate the force of the vibrations improves the sensitivity to sound and is a form of impedance matching.

However, the extent of the movements of the ossicles is controlled (and constricted) by two muscles attached to them (the tensor tympani and the stapedius). It is believed that these muscles can contract to dampen the vibration of the ossicles, in order to protect the inner ear from excessively loud noise (theory 1) and that they give better frequency resolution at higher frequencies by reducing the transmission of low frequencies (theory 2) (see acoustic reflex). These muscles are more highly developed in bats and serve to block outgoing cries of the bats during echolocation (SONAR).

Clinical relevance

Occasionally the joints between the ossicles become rigid. One condition, otosclerosis, results in the fusing of the stapes to the oval window. This reduces hearing and may be treated surgically.

History

The term ossicle dates to 1570 ossiculum, a diminutive of "bone" (Latin: os; genitive ossis). The malleus gets its name from Latin malleus, meaning "hammer", the incus gets its name from Latin incus meaning "anvil" from incudere meaning "to forge with a hammer", and the stapes gets its name from Modern Latin "stirrup," probably an alteration of Late Latin stapia related to stare "to stand" and pedem, an accusative of pes "foot", so called because the bone is shaped like a stirrup - this was an invented Modern Latin word for "stirrup," for which there was no classical Latin word, as the ancients did not use stirrups.

Additional images

• Stapes and 10 cent euro coin

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

See also

This article uses anatomical terminology; for an overview, see anatomical terminology.

• Hearing
• Ear
• Incudomalleolar joint
• Incudostapedial joint
• Middle ear
• Otolith

References

External links

• The middle ear and the ossicles

English Journal

• The second and third phases of caloric nystagmus.

• Ichijo H1.
• Acta oto-laryngologica.Acta Otolaryngol.2015 Jan;135(1):1-6. doi: 10.3109/00016489.2014.949850.
• Abstract Conclusion: The second and third phases of caloric nystagmus occur at a high rate. We can explain this phenomenon based on the hydrostatic pressure theory involved in perilymph.OBJECTIVES: To clarify the incidence of the second and third phases of caloric nystagmus, and to measure their int
• PMID 25496175

• Biomechanics of hearing in katydids.

• Montealegre-Z F1, Robert D.
• Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology.J Comp Physiol A Neuroethol Sens Neural Behav Physiol.2015 Jan;201(1):5-18. doi: 10.1007/s00359-014-0976-1. Epub 2014 Dec 17.
• Animals have evolved a vast diversity of mechanisms to detect sounds. Auditory organs are thus used to detect intraspecific communicative signals and environmental sounds relevant to survival. To hear, terrestrial animals must convert the acoustic energy contained in the airborne sound pressure wave
• PMID 25515594

• Bone quality and biomechanical function: A lesson from human ossicles.

• Duboeuf F1, Burt-Pichat B2, Farlay D3, Suy P4, Truy E5, Boivin G6.
• Bone.Bone.2014 Dec 19;73C:105-110. doi: 10.1016/j.bone.2014.12.009. [Epub ahead of print]
• In humans, the middle ear contains a chain of three ossicles with a major highly specific mechanical property (transmission of vibrations) and modeling that stops rapidly after birth. Their bone quality has been rarely studied either in noninflammatory ossicles or in those from ears with chronic inf
• PMID 25532479

Japanese Journal

• メツケル氏軟骨ノ發生學的研究 第1 哺乳類 其ノ3 Mausニ於ケルMeckelscher Knorpel及ビ下顎骨ノ發生學的研究

• 塚脇 篤太郎
• 岡山医学会雑誌 55(5), 674-696, 1943-05-31
• … Verf., der bereits bei Embryonen von Schweinen über die Entwicklung des Meckelschen Knorpels und der mit diesem in Zusammenhang stehenden Ossicula auditus berichtete und weiter dann in der vorhergehenden Mitteilung bei Embryonen von Meerschweinen hauptsächlich das Schicksal dieses Knorpels verfolgte, hat nun diesmal bei Embryonen von Mäusen die Zusammenhänge desselben mit dem Unterkiefer in der Entwicklung als A bschluss seiner diesbezüglichen Studien eingehends untersucht und ist zu folgenden …
• NAID 120002828075

Related Links

• ossicula auditus - definition of ossicula auditus by Medical ...

Definition of ossicula auditus in the Medical Dictionary. ossicula auditus explanation. Information about ossicula auditus in Free online English dictionary. What is ossicula auditus? Meaning of ossicula auditus medical term. What ...

• The ossicula auditus. (書籍, 1900) [WorldCat.org]

図書館でこの資料を入手！ The ossicula auditus.. [John Sterling Kingsley] ... 注：引用情報は参照基準に基づくものですが、書式のルールは論文の提出先や研究分野によって異なります。提出先の出版社や教官、機関、団体が指定する ...

Related Pictures

---

★リンクテーブル★

リンク元	「耳小骨」「ear ossicle」
関連記事	「audit」

「耳小骨」

　　[★]

英

auditory ossicles, ossicles

ラ

ossicula auditus

• ツチ骨、キヌタ骨、アブミ骨

Henry Gray (1825-1861). Anatomy of the Human Body. 1918.
Henry Gray (1825-1861). Anatomy of the Human Body. 1918.
Henry Gray (1825-1861). Anatomy of the Human Body. 1918.

「ear ossicle」

　　[★]

耳小骨

関

ossicula auditus

「audit」

　　[★]

• n.

• (会計)監査、審査

• v.

• 監査する

関

exploration、inspect、inspection、judge、judgement、judgment