The so-called condyloid foramen in the half axial view.
D002552:Cerebral Ventricles / Q000002:abnormalities*; D000013:Congenital Abnormalities / Q000000981:diagnostic imaging; D005539:Foramen Magnum / Q000000981:diagnostic imaging*; D006801:Humans; D010579:Petrous Bone / Q000000981:diagnostic imaging*; D011859:Radiography; D012886:Skull / Q000000981:diagnostic imaging*