As of the latest update, Google Chrome and Microsoft Edge have made a breaking change to how file uploads are handled. Once your system installs this update, you will not be able to upload new images. Please use another browser until we can get it fixed.

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.

Anatomy: Head and neck

Anatomy: Head and neck

Share article

Article information

rID: 1635
System: Head & Neck
Section: Anatomy
Tag: 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

Support Radiopaedia and see fewer ads

Cases and figures

  • Figure 1: McEwen triangle
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.