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Middle Ear - Incus

Left incus. A. From within. B. From the front.

  • named from resemblance to an anvil
    • more like a premolar tooth, with two roots, which differ in length, and are widely separated from each other.
  • consists of a body and two crura
Adult Incus Anatomy
Component Description
Body (corpus incudis) somewhat cubical but compressed transversely anterior surface is a deeply concavo-convex facet facet articulates with the head of the malleus
Short Crus (crus breve; short process) somewhat conical in shape projects almost horizontally backward attached to the fossa incudis, in the lower and back part of the epitympanic recess
Long Crus (crus longum; long process) descends nearly vertically behind and parallel to the manubrium of the malleus bending medialward, ends in a rounded projection, the lenticular process lenticular process is tipped with cartilage, and articulates with the head of the stapes


(text modified from Gray's Anatomy)


Development

Human incus development timing:[1]

  • 16 weeks - force lines start through two cortical fascicles in the long process
  • 17 to 20 weeks - two cortical fascicles progressively extend in a rostro-caudal direction
  • 21 weeks - occupy the whole extension of the long process
  • 22 weeks - fusion of both cortical fascicles begins.
  • 30 weeks - strengthened by the crossing of bone trabeculae from one cortical to another. Two fascicles come out of the incus body, surrounding the medullary cavity and going in the direction of the short process.


  1. <pubmed>18581276</pubmed>



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Pages where the terms "Historic Textbook" and "Historic Embryology" appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)
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Reference

Gray H. Anatomy of the human body. (1918) Philadelphia: Lea & Febiger.


Cite this page: Hill, M.A. (2019, January 19) Embryology Gray0917.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Gray0917.jpg

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