Fig. 43-19. Internal carotid angiograms in vivo. A, lateral view. B, Postero-anterior view. The numerals from 1 to 7 refer to successive parts of the internal carotid artery. Number 7 is in the neck, number 6 lies within the carotid canal, number 5 is medial to the trigeminal ganglion, numbers 4 to 2 constitute the carotid siphon (which gives off the ophthalmic artery, Oph.), and number 1 ascends to the division into anterior (A) and middle (M) cerebral arteries. (Courtesy of Arthur B. Dublin, M.D., Sacramento, California.) Click for high resolution image.