Cerebrovascular Anatomy

Cerebrovascular Anatomy – Arterial

All named arteries are in italics
External Carotid Artery – 8 branches (SALFOPS)

Superior thyroid – larynx, upper thyroid (rest of thyroid supplied by branch of thyrocervical trunk)
Ascending pharyngeal – nasopharynx, oropharynx, middle ear, CN IX/X/XI, meninges; has anastemoses with vertebral artery
Lingual – tongue and floor of mouth
Facial – face, palate, lips; angular branch anastemosis with orbital branch of ophthalmic
Occipital – posterior scalp, upper cervical musculature, posterior fossa meninges
Posterior auricular – pinna, external auditory canal, scalp
Superficial temporal – scalp and ear

o Internal maxillary – deep face; supplies middle meningeal; ethmoidal branches anastemose with inferolateral cavernous sinus and ophthalmic artery

Internal Carotid Artery – 4 segments

(1) Cervical – no branches; lies posterolateral to ECA
(2) Petrosal (intraosseous) – in carotid canal of petrous temporal bone

Caroticotympanic – middle/inner ear; anastemosis with anterior tympanic branch of maxillary artery
Vidian (artery of pterygoid canal) – foramen lacerum, vindian canal; anastemosis with external carotid branches

§ Persistent stapedial artery – provides middle meningeal if no foramen spinosum develops

(3) Intracavernous – 3 branches

(a) Posterior (meningohypophyseal trunk)

tentorial artery of Bernasconi and Cessinari (tentorium)
inferior hypophyseal artery (posterior pituitary capsule)

· dorsal meningeal (CN VI, part of clivus)

(b) Lateral (inferior cavernous sinus artery) – inferior wall of cavernous, foramina ovale/spinosum

§ (c) Medial (McConnel’s capsular artery) – anterior and inferior pituitary capsule (present in only 28%)

(4) Intradural (supraclinoid)

Ophthalmic – sometimes intracavernous or even middle meningeal (0.5%, blindness with middle meningeal embolization)

inferior then superolateral to optic nerve, supplies orbit via central retinal artery and ciliary branches (orbit also supplied by infraorbital branch of the maxillary artery)

· aneurysms point superior and can compress optic nerve (arise on superior ICA distal to origin)

superior hypophyseal – off inferolateral wall of ICA beneath optic nerve; supplies pituitary stalk, tuber cinereum, anterior lobe of the pituitary, inferior chiasm

· aneurysms point inferior and medial

Pcomm – off inferolateral wall of ICA, travels posterolateral above CNIII to anastemose with PCA

50% anomalous (such as fetal PCA where Pcomm caliber equals PCA, found in 30% bilateral in 8%)
Perforators to posterior hypothalamus, anterior thalamus, posterior internal capsule, and subtahalamus
Anterior thalamoperforators (largest perforators between mamillary bodies and optic tract)

· Aneurysms point posterolateral and can compress CNIII (arise from posterior wall of carotid distal to Pcomm); Pcomm aneurysms are usually superomedial to Pcomm and inferolateral to anterior choroidal

Anterior choroidal – off posterior ICA 2-4 mm distal to pcomm, inferolateral to the optic tract

Cisternal segment – through supracellar cistern, posteromedially around uncus then posterolaterally through crural and ambient cisterns to enter choroidal fissure (“plexal point”)

o Perforators to inferior optic chisam, posterior optic tract, globus pallidus, internal capsule (genu), middle part of cerebral peduncle, substantia nigra, upper red nucleus, subthalamus, and lateral VA and VL thalamus

Plexal segment – supplies choroids plexus of anterior lateral ventricle

o Perforators to lateral half of geniculate body, internal capsule (inferior posterior and retrolenticular), optic radiations, and choroid plexus

· aneurysms arise superior or superolateral to origin

Anterior Cerebral Artery – 25% are anomalous (azygous), which have higher risk of aneurysms; 3 segments

(1) A1 (precommunicating) – prior to Acomm

Medial lenticulostriate (usually about 8) – superior surface of optic nerve and chiasm, anterior hypothalamus, septum pellicidum, anterior commissure, pillars of fornix, anteroinferior striatum
Medial proximal striate (Huebner is medial distal striate, from A2)
Acomm – in cistern of lamina terminalis, supplies 2 perforators to infundibulum, chiasm, subcallosal area, preoptic hypothalamus, “subcallosal artery” and “medial artery of corpus callosum”

§ Acomm aneurysms arise from the dominant A1 and point toward the opposite side

(2) A2 (proximal pericallosal)

Medial distal striate (Recurrent Artery of Huebner) – courses back toward proximal A1 and enters anterior perforating substance to supply head of caudate, anterior internal capsule, anterior globus pallidus and putamen, septal nuclei, and inferior frontal lobe
Orbitofrontal – gyrus rectus, medial orbibtal gyrus, olfactory bulb and tract
Frontopolar – medial frontal lobe and lateral surface of superior frontal gyrus

§ Anterior inferior frontal – anteromedial frontal lobe

(3) A3 – supplies anterior 2/3 of medial cortex

Callosalmarginal – cingulate gyrus, paracentral lobule

Medial inferior frontal
Posterior inferior frontal

· Paracentral – central sulcus

Distal Pericallosal – medial parietal cortex, precuneus

Superior parietal

· Inferior parietal

Middle Cerebral Artery – sylvian point is the most posterior branch, lies 5 cm from midline on AP projection

(1) M1 – to M2 bifurcation

Uncal (often from distal ICA)
Temperopolar – temporal tip
Anterior temporal

§ Lateral lenticulostriate (usually 2-15) – supply inferomedial substantia innomonata, lateral anterior commissure, putamen, lateral globus pallidus, superior internal capsule, and caudate

(2) M2 – to opercular branches leaving Sylvian fissure; 2 branches

(a) Superior trunk

Orbitofrontal – middle/inferior frontal gyri, inferior pars orbitalis
Prefrontal – superior pars orbitalis, pars triangularis, anterior pars opercularis, part of middle frontal gyrus
Precentral – posterior pars opercularis, middle frontal gyrus, inferior and medial precentral gyrus
Central – superior postcentral gyrus, upper central sulcus, anterior inferior parietal lobule

· Anterior parietal – superior parietal lobule

(b) Inferior trunk

Middle temporal – superior temporal gyri, central middle temporal gyrus, posterior inferior temporal gyrus
Posterior temporal – middle/posterior superior temporal gyrus, posterior middle and extreme posterior inferior temporal gyrus
Temperooccipital – posterior half of superior temporal gyrus, posterior extreme middle temporal gyurs, inferolateral occipital lobe
Angular – posterior aspect superior temporal gyurs, portions of supramarginal and angular gyri, superior aspect of lateral occipital lobe

· Posterior parietal – posterosuperior and inferior parietal lobule, inferior supramarginal gyrus

o (3) M3 branches are continuations of the above

Vertebral – from subclavian artery (5% from aorta on left); enters foramen transversarium at C6, exits laterally at C2, travels posteriorly along atlas and enters foramen magnum; 50% left dominant, 25% right dominant, 40% have one hypoplastic; anastemoses with ECA and branches of thyrocervical and costocervical trunks

Perforators supply pyramids, inferior olive, vagal and hypoglossal nuclei, and reticular formation
Posterior spinal – gracilis and cuneatis, inferior cerebellar peduncle
Anterior spinal – pyramid, medial lemniscus, medial longitudinal fasciculus, inferior olive, vagal/hypoglossal nuclei
PICA (occasionally arises extracranially, 25% of vertebral arteries end in PICA) – 4 segments (Anterior medullary, Lateral medullary (CNIX/X/XI), Tonsillomedullary, Telovelotonsilar); supplies choroids plexus of 4^th ventricle, posterior lateral medulla, tonsils, vermis, posterior inferior hemispheres

§ Wallenburg’s syndrome – crossed pain/temperature (ipsilateral face), ipsilateral laryngeal paralysis/ataxia/Horner’s

o Posterior meningeal (near atlas and falx cerebelli) – also contributions from ECA branches (occipital, ascending pharyngeal)

Basilar

AICA – crosses CNVI and CPA cistern to internal acoustic canal, anterior/inferior to CN VII/VIII; supplies CNVII/VIII, inferolateral pons, middle cerebellar peduncle, flocculus, anterolateral cerebellar hemispheres

Internal auditory
Recurrent perforating arteries

§ Subarcuate

Labarinthine
Paramedian branches –ventral pons and midbrain
Long and short circumferential arteries – ventral pons, anastemose with AICA at middle cerebellar peduncle
SCA – below CN III/IV to superior vermis and hemispheres of cerebellum, deep white matter, deep nuclei

Weber – ipsilateral CNIII, pyramid (contralateral body motor deficit)

§ Benedikt – ipsilateral CNIII, red nucleus (tremor), cerebellar peduncle (cerebellar dentothalamic fibers)

Posterior Cerebral Artery – supplies inferior temporal gyrus, most of occipital lobe, superior parietal lobule, brainstem, and choroid of 3^rd/lateral ventricles

(1) P1 – peduncular cistern to Pcomm

Posterior thalamoperforators – to thalamus and midbrain
Medial posterior choroidal artery – anteromedial along rostral 3^rd ventricle to supply midbrain tectum, posterior thalamus, pineal, and choroid plexus of 3^rd ventricle (not lateral)

(2) P2 – in ambient cistern from Pcomm to quadrigeminal plate, around midbrain above CNIV and tentorial incisura

Lateral posterior choroidal – thalamus, choroid plexus of lateral ventricles (anastemosis with anterior choroidal)
Medial and lateral thalamogeniculate – medial and lateral geniculate bodies, pulvinar, superior colliculus, crus cerebri, pineal

(3) P3 – starts posterior to midbrain

Posterior temporal – posterior temporal lobes, occipital/temporal/lingual gyri

Anterior temporal branches – inferior temporal lobes, anastemose with MCA branches

Internal occipital

Patietooccipital – posterior 1/3 of cerebral hemispheres, anastemoses with ACA
Calcarine – occipital pole anastemoses with MCA
Posterior pericallosal – supplies splenium of corpus callosum, anastemses with ACA

Summary of perforators

Anteromedial

From: ACA, Acomm
To: anterior perforating substance to anterior pituitary, supraoptic, preoptic nuclei

Anterolateral

From: MCA, ACA (Huebner)
To: striatum, internal capsule

Posteromedial

From: PCA, Pcomm
To: pituitary, infundubulum, tuberal hypothalamus; thalamoperforators also supply mamillary bodies, subthalamus, and midbrain

Posterolateral

From: PCA (thalamogeniculate)
To: caudal thalamus

Supply to Internal Capsule

Lateral/rostral anterior – supplied by lenticulostriate (MCA)
Genu – supplied by ICA perforators
Caudal posterior and retrolenticular – supplied by anterior chroidal
Rostral posterior – supplied by Huebner
Caudal posterior – supplied by Pcomm

EC-IC Anastemoses

Ascending pharyngeal to vertebral artery (C3) and petrous/cavernous branches of ICA
Facial (angular) to ophthalmic (orbital)
Occipital to vertebral (C1C2)
Posterior auricular to ICA (stylomastoid)
Maxillary to ICA:

Middle meningeal to ophthalmic (ethmoidal)
Artery of foramen rotundum/accessory meningeal to inferolateral trunk of ICA
Vidian artery to infratemporal ICA
Anterior and deep temporal arteries to ophthalmic (lacrimal, palpebral, muscular)

Persistant fetal carotid-vertebral anastemoses (higher risk of aneurysm)

Primitive trigeminal – most common (besides fetal PCA), 0.1-0.5%

From: ICA (usually proximal to cavernous sinus) or meiningohypophyseal trunk
To: basilar artery between SCA and AICA

Persistent otic/acoustic – through internal acoustic meatus

From: petrous ICA
To: basilar

Persistent hypoglossal – 2^nd most frequent, 0.1%; through hypoglossal canal

From: cervical ICA
To: basilar

Proatlantal intersegmental artery

From: ECA or cervical ICA
To: vertebral artery between C1 and occiput

Blood Supply to Dura

Anterior meningeal artery – from ophthalmic
Middle meningeal artery – from maxillary branch of external carotid
Posterior meningeal – from occipital and vertebral arteries