The foramen mastoideum is a variable bony opening in the posterior part of the Temporal bone.
Anatomy
The foramen mastoideum forms a connection between the Sulcus sinus sigmoidei and the external surface of the Processus mastoideus. It contains a mastoid emissary vein to the Sinus sigmoideus and the posterior meningeal branch of the Arteria occipitalis.
Variability
The foramen mastoideum is highly variable and may consist of between 0 and 4 openings[^1].
Figure
