Reference tables for cerebral vascular anatomy — arterial segments, branches, territories, and associated occlusion syndromes.
Internal Carotid Artery
The ICA is divided into 4 anatomical segments (cervical, petrous, cavernous & cerebral) and 7 angiographic segments (Bouthillier classification) as detailed below.
| ICA Segment | Branches |
|---|
| C1 Cervical | None |
| C2 Petrous (horizontal) | Vidian, Caroticotympanic |
| C3 Lacerum | None |
| C4 Cavernous | Meningeohypophyseal, capsular, inferolateral trunk |
| C5 Clinoid | None |
| C6 Ophthalmic (supraclinoid) | Ophthalmic, superior hypophyseal |
| C7 Communicating (terminal) | Posterior communicating, anterior choroidal |
| Mnemonics |
- Segments (CPL CCST)
- Branches (VIP’s COM): Vidian, inferolateral trunk, PCOM, superior hypophyseal, Caroticotympanic, ophthalmic, Meningeohypophyseal
|
Internal Carotid Artery Branches — Clinical Significance
| Branch | Location | Clinical significance |
|---|
| C2 Caroticotympanic | Enters middle ear | Anastomose with inferior tympanic branch of ECA (enlarges in cases of aberrant ICA ‘absent C1 segment’) |
| C2 Vidian | Pterygopalatine fossa | Anastomose with vidian branch of internal maxillary of ECA |
| C4 Meningeohypophyseal | |
- Marginal tentorial: tentorial dura
- Clival: clival dura
- Inferior hypophyseal: pituitary
|
| C4 Inferolateral Trunk | Runs in inferolateral direction in the cavernous sinus |
- Anterior branch: through superior orbital fissure, anastomose with recurrent meningeal branch of ophthalmic artery
- Posterior branch: along abducent to supply tentorial dura
- Third branch: anastomose with accessory meningeal artery
- Fourth branch: supply V2 division of trigeminal nerve (maxillary)
|
| C6 Ophthalmic | Runs in optic canal |
- Orbital branches: lacrimal, supraorbital, supratrochlear, ethmoidal
- Ocular branches: central retinal, anterior ciliary, posterior ciliary
|
| C6 Superior Hypophyseal | | Supplies optic nerve, chiasm, pituitary gland |
| C7 PCOM | |
- Supplies posterior part of optic nerve, chiasm, hypothalamus, mammillary bodies
- Anterior thalamoperforating (premamillary a.)
|
| C7 Anterior Choroidal |
- Choroidal fissure segment
- Intraventricular segment
|
- Supplies optic tract, LGB, lateral thalamus, posterior limb of internal capsule, lateral midbrain
- Supplies choroid plexus in temporal horn
|
Occlusion Syndromes
| Occluded artery | Occlusion syndrome |
|---|
| Ophthalmic Artery | Loss of vision with no cherry red spot (worse than CRAO) |
| Central retinal artery |
- CRAO: sudden, acute, and painless loss of vision in one eye. Fundus with cherry red spot (pale retina)
- Prognosis: 65% will lose vision (worse than 20/400) – only 15% will regain their vision (better than 20/40)
|
| Posterior Ciliary | AION: ischemia of optic nerve head due to decrease blood flow in circle of Zinn (made by medial & lateral posterior ciliary arteries around optic nerve head). Manifests as altitudinal field defect (commonly inferior). GCA is a major cause of AION (median age 72, more in women, 50% of patients have PMR). |
| Anterior Ciliary | Multiple small arteries, rarely to manifest clinically. |
| Posterior Communicating | Uncommon |
| Anterior Thalamoperforating | Personality changes, apathy, abulia |
| Anterior Choroidal Artery | Hemiparesis, hemihypothesia, hemianopia and neglect. Sometimes mutism which is considered a form of neglect |
External Carotid Artery
| ECA Branch | Intracranial Supply |
|---|
| Superior thyroid | None |
| Ascending Pharyngeal | Neuromeningeal branch → dura and lower cranial nerves |
| Lingual | |
| Facial | Angular branch → anastomosis with ophthalmic artery branches |
| Occipital | Anastomosis with vertebral artery segmental branches |
| Superficial temporal | |
| Internal Maxillary | Middle meningeal artery → supplies dura through foramen spinosum |
Middle Cerebral Artery
| Segment | Location | Branches |
|---|
| M1 | Main trunk | Lenticulostriate – deep penetrating vessels |
| M2 | In Sylvian fissure where it divides | Superior and inferior divisions |
| M3 | Cortical segment | Cortical branches |
| M4 | Over cortical surface | Cortical branches |
Posterior Cerebral Artery
| Segment | Location | Branches |
|---|
| P1 | From basilar to PCOM origin, in interpeduncular cistern |
- PCOM → anterior thalamoperforator
- Posterior thalamoperforator
|
| P2 |
- From PCOM origin
- P2A: while in the crural cistern
- P2P: after bridging to ambient cistern
|
- Middle posterior choroidal artery
- Lateral posterior choroidal artery
- Thalamogeniculate
|
| P3 | Quadrigeminal cistern | |
| P4 | Cortical branches |
- Anterior & posterior temporal arteries
- Lateral occipital artery
- Medial occipital artery → calcarine & parieto-occipital
- Splenial artery
|
Basilar Artery Branches
| Branch | Supply |
|---|
| Paramedian | Supplies medial third of pons, midbrain |
| Short circumferential | Supplies lateral 2/3 of pons, midbrain |
| Long Circumferential | AICA & SCA (superior cerebellar artery) |
| Interpeduncular | Supplies high midbrain and subthalamic |
Ahmed Koriesh, MD
