Macewen’s triangle

What is the Macewen's triangle?

Macewen's triangle is the most important surgical landmark for the mastoid antrum or the largest mastoid air cell.

What are the boundaries of Macewen's triangle

Boundaries of Macewen's triangle are as follows:

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

In an adult, the mastoid antrum lies at a depth of approximately 1.5 cm from this triangle.