MacEwen triangle

The MacEwen triangle (also called the suprameatal triangle or mastoid fossa) is a small triangular depression affecting the inner table of the temporal bone.

The lines forming the triangle are:

History and etymology

It is named after Sir William MacEwen (1864-1924), Scottish surgeon.

Related pathology

The cortical bone is particularly thin making a preferred route of subperiosteal abscess (mastoid) formation, secondary to coalescent mastoiditis.

The mastoid antrum lies 1 cm deep to the triangle in the adult and is used when performing a cortical mastoidectomy.


Head and neck anatomy
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Article Information

rID: 1635
System: Head & Neck
Section: Anatomy
Tags: ent, refs
Synonyms or Alternate Spellings:
  • Macewen's triangle
  • MacEwen triangle
  • MacEwen's triangle
  • Suprameatal triangle
  • Mastoid fossa
  • Foveola suprameatica
  • McEwen's triangle
  • MacEwan's triangle
  • McEwan's triangle
  • MacEwens triangle

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    Figure 1: McEwen triangle
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