Fig 1.

Schematic representation of the ICA segmentation.

The ICA is divided into eight segments: 1) cervical, 2) ascending petrous, 3) horizontal petrous, 4) ascending cavernous, 5) horizontal cavernous, 6) clinoid, 7) ophthalmic, and 8) terminal. In the classification proposed by Lasjaunias and Santoyo-Vazquez (1), segments 7 and 8 are grouped as a single terminal segment, for a total of seven segments. In the nomenclature proposed by Fischer in 1938 (10), C1, C2, C3, C4, and C5 correspond to the segments 8, 7, 6, 5, and 4, respectively. CT, caroticotympanic artery; ECA, external carotid artery; ILT, inferolateral trunk; MHT; meningohypophyseal trunk; OA, ophthalmic artery; PcomA, posterior communicating artery; VID, vidian artery.