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Macewen’s triangle

1. The area in the temporal bone in between the posterior wall of the external acoustic meatus and the posterior root of the zygomatic process through which an instrument may be pushed into the mastoid antrum. (

2. Macewen’s triangle is the most important surgical landmark for the mastoid antrum or the largest mastoid air cell. The boundaries include:

  • Superiorly: Suprameatal crest
  • Anterior-inferiorly: Posterior margin of external auditory canal
  • Posteriorly: A tangential line from the posterior canal wall cutting the suprameatal crest


Syn: suprameatal triangle, suprameatal pit, mastoid fossa, foveola suprameatica

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