The outer surface of the temporal bone
is perforated by numerous foramina
; one of these, of large size, situated near the posterior border, is termed the mastoid foramen
It transmits a vein to the transverse sinus and a small branch of the occipital artery to the dura mater.
The position and size of this foramen are very variable; it is not always present; sometimes it is situated in the occipital bone
, or in the suture
between the temporal and the occipital.