Drtbalu at 04:17, 10 October 2018

2018-10-10T04:17:27Z

Drtbalu at 04:15, 10 October 2018

2018-10-10T04:15:30Z

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Drtbalu: Created page with " Category:Otology"

2018-10-10T02:31:50Z

Created page with " Category:Otology"

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[[Category:Otology]]

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 Pyramidis a small conical projection which is hollow and its apex pointing anteriorly. It contains the stapedius muscle, the tendon of which passes forwards to insert into the neck of the stapes. The canal within the promontory curves downwards and backwards to join the descending portion of the facial nerve canal. Between the promontory and the tympanic annulus is the facial recess. The facial recess is bounded medially by the facial nerve and laterally by the tympanic annulus.Running through the wall between the two with varying degrees of obliquity is the chorda tympani nerve. This nerve always run medial to the tympanic membrane. Drilling over the facial recess area between the facial nerve and the annulus in the angle formed by the chorda tympani nerve can lead into the middle ear cavity. This surgical approach to the middle ear cavity through this area is known as the facial recess approach. This approach is suitable for surgeries involving the round window niche like placement of electrodes during cochlear implant procedures. Hypotympanum can also be approached through this approach.
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 === Contents of the middle ear: ===
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 This bone is shaped like a hammer hence the name. This is the largest of the three ossicles of the middle ear cavity. It has a head, neck and three processes arising from below the neck. The overall length of the malleus ranges between 7.5 - 9 mm. Its head lies in the attic region of the middle ear effectively dividing the attic into an anterior portion and a posterior one. The anterior portion lie anterior to the handle of the malleus, while the posterior portion lie behind the handle of the malleus. During surgical procedures for attic cholesteatoma clipping of this head will improve the exposure in the attic region. The head of the malleus on its posterio medial surface has an elongated saddle shaped cartilage covered facet for articulation with the incus. This articular surface is constricted near its middle dividing the articular facet into a larger superior and a smaller inferior portions. The inferior portion of the articular facet lies at right angles to that of the superior portion. This projecting lower portion is also known as the cog or spur of the malleus. Below the neck the bone broadens and gives rise to the following: the anterior process from which a slender anterior ligament arises to insert into the petrotympanic fissure; the lateral process which receives the anterior and posterior malleolar folds from the annulus tympanicum, and the handle which runs downwards,medially and slightly backwards between the mucous and fibrous layers of the tympanic membrane. On the deep medial surface of the handle there is a small projection into which the tendon of the tensor tympani muscle inserts. Additionally the malleus is supported by the superior ligament which runs from the head to the tegmen tympani.
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 Incus:
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 This bone is shaped like an anvil. It articulates with the malleus and has a body and two processes. The body lies in the attic and has a cartilage covered articular facet corresponding to that of the malleus. The short process projects backwards from the body to lie in the fossa incudis. It is in fact attached to the fossa incudis by a short ligament. The long process of the incus descends into the mesotympanum behind and medial to the handle of the malleus. At its tip there is a small medially directed lenticular process which articulates with the stapes. The long process of the incus has precarious blood supply. This portion of the incus is prone for undergoing necrosis in disease conditions.
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 The stapes:
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 the stapes gives rise to two crura, the anterior crura is thinner and less curved than the posterior crura. The two crura join the foot plate which closes the oval window during life. The average dimensions of the foot plate is 3mm x 1.4mm. The long axis of the foot plate is almost horizontal, with the posterior end being slightly lower than the anterior.
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 Muscles of the middle ear:

Anatomy of Middle Ear - Revision history

Drtbalu at 04:17, 10 October 2018

Drtbalu at 04:15, 10 October 2018

Drtbalu: Created page with " Category:Otology"