Incus

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Incus
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Left incus. A. From within. B. From the front.
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Auditory tube, laid open by a cut in its long axis.
Details
Pronunciation /ˈɪŋkəs/
Precursor First branchial arch [1]
Part of Middle ear
Articulations Incudomalleolar and incudostapedial joint
Identifiers
Latin incus
MeSH D007188
TA98 A15.3.02.038
TA2 888
FMA 52752
Anatomical terms of bone

The incus (pl.: incudes) or anvil in the ear is one of three small bones (ossicles) in the middle ear. The incus receives vibrations from the malleus, to which it is connected laterally, and transmits these to the stapes medially. The incus is named for its resemblance to an anvil (Latin : incus).

Contents

Structure

The incus is the second of three ossicles, very small bones in the middle ear which act to transmit sound. It is shaped like an anvil, and has a long and short crus extending from the body, which articulates with the malleus. [2] :862 The short crus attaches to the posterior ligament of the incus. The long crus articulates with the stapes at the lenticular process.

The superior ligament of the incus attaches at the body of the incus to the roof of the tympanic cavity.

The incus is homologous to the quadrate bone found in other tetrapods. [3]

Function

Vibrations in the middle ear are received via the tympanic membrane. The malleus, resting on the membrane, conveys vibrations to the incus. This in turn conveys vibrations to the stapes. [2]

History

"Incus" means "anvil" in Latin. Several sources attribute the discovery of the incus to the anatomist and philosopher Alessandro Achillini. [4] [5] The first brief written description of the incus was by Berengario da Carpi in his Commentaria super anatomia Mundini (1521). [6] Andreas Vesalius, in his De humani corporis fabrica , [7] was the first to compare the second element of the ossicles to an anvil, thereby giving it the name incus. [8] The final part of the long limb was once described as a "fourth ossicle" by Pieter Paaw in 1615. [9]

Additional images

Related Research Articles

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The incudomalleolar joint or articulatio incudomallearis is a small synovial joint between the malleus (hammer) and the incus (anvil). The joint's function is to transfer vibrations between the ossicles in the middle ear, which is perceived as sound. Contrary to other synovial joints the movement is very limited. All of the ossicles move more or less as a unit, at least at low frequencies.

<span class="mw-page-title-main">Incudostapedial joint</span> Small joint between the incus and the stapes

The incudostapedial joint is a small, synovial ball-and-socket joint between the incus (anvil) and the stapes (stirrup). The joint's function is to transfer vibrations between the two ossicles. The incudostapedial joint lies between the long leg of the incus and the head of the stapes. The long leg moves with the rest of the incus, and a small knob, the lenticular process, articulates with the head of the stapes.

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<i>Malleus</i> Bone of the middle ear

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 from the eardrum to the incus (anvil).

References

  1. hednk-023 —Embryo Images at University of North Carolina
  2. 1 2 Drake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students. Philadelphia: Elsevier/Churchill Livingstone. ISBN   978-0-8089-2306-0.
  3. Luo, Zhexi; Crompton, Alfred W. (1994-09-07). "Transformation of the quadrate (incus) through the transition from non-mammalian cynodonts to mammals". Journal of Vertebrate Paleontology. 14 (3): 341–374. doi:10.1080/02724634.1994.10011564. ISSN   0272-4634.
  4. Alidosi, GNP. I dottori Bolognesi di teologia, filosofia, medicina e d'arti liberali dall'anno 1000 per tutto marzo del 1623, Tebaldini, N., Bologna, 1623. http://gallica.bnf.fr/ark:/12148/bpt6k51029z/f35.image#
  5. Lind, L. R. Studies in pre-Vesalian anatomy. Biography, translations, documents, American Philosophical Society, Philadelphia, 1975. p.40
  6. Jacopo Berengario da Carpi,Commentaria super anatomia Mundini, Bologna, 1521. https://archive.org/details/ita-bnc-mag-00001056-001
  7. Andreas Vesalius, De humani corporis fabrica. Johannes Oporinus, Basle, 1543.
  8. O'Malley, C.D. Andreas Vesalius of Brussels, 1514-1564. Berkeley: University of California Press, 1964. p. 121
  9. Graboyes, Evan M.; Chole, Richard A.; Hullar, Timothy E. (September 2011). "The Ossicle of Paaw". Otology & Neurotology. 32 (7): 1185–1188. doi:10.1097/MAO.0b013e31822a28df. PMC   3158805 . PMID   21844785.