Know all the blood vessels supplying the Brain and spinal cord and varieties of stroke in brain for neurology and Neurosurgery residents

1. BLOOD SUPPLY OF BRAIN
Dr SAMEEP KOSHTI

2. • The intracranial circulation :
• divided into anterior and posterior circulation,
• on the basis of internal carotid artery and vertebral artery supply respectively.
• Anterior circulation :
• anterior choroidal artery
• anterior cerebral artery (ACA)
• middle cerebral artery (MCA)
• Posterior circulation :
• posterior cerebral artery (PCA)
• basilar artery
• superior cerebellar artery (SCA)
• anterior inferior cerebellar artery (AICA)
• posterior inferior cerebellar artery (PICA)

3. A, Frontal view of a right carotid angiogram. 1, Intraparietal
sulcus; 2, M3 branches on the planum temporale; 3, M3
branches in the central sulcus region; 4, lateral lenticulostriate
arteries; 5, M3 branches in the anterior limiting sulcus of the
insula; 6, genu of the middle cerebral artery; 7, internal carotid
artery (supraclinoid segment); M, “M point” or “sylvian point.”
B, Lateral view of a carotid angiogram. The blue arrows
indicate the superior limiting sulcus of the insula, the red arrows
indicate the inferior limiting sulcus of the insula, and the yellow
arrow indicates the anterior limiting sulcus of the insula.

4. Ant.Choroidal Artery
• Origin:
• from the posterior wall of the Internal Carotid Artery
• between the origin of the posterior communicating artery (PCOM) (which is 2-5 mm proximal to
the AChA) and the internal carotid termination (which is 2-5 mm distal to the AChA).
• It measures ~1 mm in diameter.
• Segments:
• cisternal segment:
• optic tract
• lateral geniculate nucleus and lateral aspect of the thalamus
• the retrolenticular and posterior portions of the posterior limb of the internal capsule
• lateral aspect of the midbrain
• uncus ,globus pallidus,
• intraventricular segment:
• choroid plexus of the anterior part of the temporal horns of the lateral ventricles

5. ANTERIOR CHOROIDAL ARTERY SYNDROME
• rare entity characterised
• by the triad of :
• Contralateral hemiplegia,
• Contralateral hemianaesthesia and
• contralateral homonymous hemianopia
• as a result of cerebral infarction in the anterior choroidal artery territory.
• May also be associated with neuropsychological disorders, including :
• left neglect syndrome in right-sided lesions and
• disorders of speech in left-sided lesions.
• Incomplete forms of the syndrome are more common than that of complete forms.

10. Anterior choroidal
artery infarct

11. ANTERIOR CEREBRAL ARTERY
• forms at the termination of the internal carotid artery
• Arches anteromedially to pass anterior to the genu of the corpus callosum,
• dividing into its two major branches; pericallosal and callosomarginal arteries
• It supplies:
• the medial aspect of the cerebral hemispheres back to the parietal lobe.
• five segments:
• The A1 segment
• from the bifurcation of the ICA to the anterior communicating artery (ACom).
• The A2 segment
• from the ACom to the junction between the rostrum and the genu of the corpus callosum.
• The A3 segment
• extends from the genu of the corpus callosum to the point where the artery turns sharply and posteriorly above the genu of
the corpus callosum.
• The A4 and A5 segments
• from the genu to the splenium.
• The A2 and A3 segments together are also called the ascending segment.
• The A4 and A5 segments together are also called the horizontal segment,
• The segment of the ACA distal to the ACom (A2 to A5) has also been called the pericallosal artery).
• The junction of the ACom with the A1 segment occurs above the chiasm in 70% of individuals and above the
nerve in 30%.

12. • A1
• The medial lenticulostriate perforators,
• 1 to 11 branches
• Supplies Medial Ant.perforated Substances
• ACom artery
• A2
• Recurrent artery of Heubner
• central or the basal perforating arteries,
• The two first cortical branches of the ACA supplying the medial surface, the orbitofrontal
and the frontopolar arteries.
• A3 to A5
• cortical branches and supply the medial surface of the hemisphere.

22. Acom artery
• it demarcates the junction between the A1 and A2 segments of the
anterior cerebral artery.
• Branches
• cingulate gyrus
• anterior columns of the fornix
• optic chiasm
• lamina terminalis
• hypothalamus
• para-olfactory areas

24. MIDDLE CEREBRAL ARTERY
• arises from the internal carotid artery (ICA),
• coursing laterally into the lateral sulcus where it branches and provides many
branches that supply the cerebral cortex.
• Four Segments:
• the M1 or sphenoidal / Horizontal segment :
• from the bifurcation of the internal carotid artery (ICA) to the limen insulae
• The M2 or insular segment :
• from the limen insulae to the superior and inferior circular sulci of the insula;
• it runs in the insular compartment of the sylvian fissure
• The M3 or opercular segment :
• From the superior or inferior circular sulcus of the insula, to the opercular compartment.
• The loop of the most posterior M3 segment branch that exits from the sylvian fissure is called the M
point or the sylvian point.
• The M4 or cortical segment :
• From the sylvian fissure to the lateral surface of the cerebrum.

27. Branches of MCA segments
• M1 segments:
• medial lenticulostriate penetrating arteries
• lateral lenticulostriate penetrating arteries
• anterior temporal artery
• polar temporal artery
• uncal artery (which may branch from the anterior choroidal artery)
• M2 Segments:
• Division of the MCA is variable
• In 78 % it divides into two trunks, superior and inferior
• 12% trifucate into superior, middle and inferior divisions
• Superior terminal branch
• lateral frontobasal artery
• prefrontal sulcal artery
• pre-Rolandic (precentral) and
• Rolandic (central) sulcal arteries
• Inferior terminal branch
• three temporal branches (anterior, middle, posterior)
• branch to the angular gyrus
• two parietal branches (anterior, posterior)

32. MCA TRIFURCATION
ANEURYSM

36. POSTERIOR COMMUNICATING ARTERY
• originates from
• After the origin of ophthalmic artery ,from the posterior aspect of the C7 (communicating) segment of
the internal carotid artery and
• extends posteriormedially to anastomose with the ipsilateral posterior cerebral artery.
• Branches:
• The PCOM gives off many fine, scarcely visible, perforating branches. The largest perforating branch is called
the premamillary (or anterior thalamoperforating) artery.
• Perforators from the PCOM supply:
• posterior part of the optic chiasm and optic tract
• posterior part of the hypothalamus and mammillary bodies
• part of the thalamus
• In the embryo:
• the PCom continues as PCA, but in adults the PCA becomes part of the basilar system.
• FETAL PCA :
• If the PCom remains the major origin of the PCA, the configuration of the PCom is termed fetal .

38. • This is a PCOM infundibulum and
not an aneurysm.
• because the vessel inserts into
the apex of a funnel shaped
bulge which is no more than
4mm in size.
• These do not get bigger and do
not bleed.
• An aneurysm however would be
round and the vessel would
insert towards its base.
• An aneurysm of course can get
bigger and can bleed. The
distinction between the two is
therefore very important.

41. VERTEBRAL ARTERY
• origin: branches off the posterior superior 1st part of the subclavian artery
• course: ascends posterior to the internal carotid artery in the transverse
foramina of the cervical vertebrae
• termination: combines with the contralateral vertebral artery to form the basilar
artery
• VARIATION IN ORIGIN:
• brachiocephalic artery (on the right)
• aortic arch: 6% of cases, most on the left
• The VA is normally 3-5 mm in diameter and the ostium is the most common site
of stenosis.
• When the origin is from the arch, then it is common for the artery to enter the
foramen transversarium at a level higher than normal (C5 instead of C6).

43. • The vertebral artery is typically divided into 4 segments:
• V1 (preforaminal/extraosseous): origin to transverse foramen of C6
• behind the common carotid artery to enter the transverse foramen of C6.
• Related anteriorly: common carotid artery, vertebral vein, thoracic duct (left VA) and lymphatic
duct(right VA)
• V2 (foraminal): from the transverse foramen of C6 to the transverse foramen of C2
• It then turns superolaterally through the inverted L-shaped transverse foramen of C2.
• V3 (atlantic, extradural or extraspinal): from C2 to the dura
• V3 emerges from the transverse process of C2 (axis),
• and sweeps laterally to pass through the transverse foramen of C1 (atlas).
• From here it passes around the posterior border of the lateral mass of C1 and below the inferior
border of the posterior atlanto-occipital membrane lateral to the cervico-medullary junction.
• Passing superomedially it pierces the dura and arachnoid to continue as V4. This tortuosity
provides length and freedom for the vessel to stretch, straighten and bend during rotation of the
head, which occurs at the atlanto-axial joints.
• V4 (intradural or intracranial): from the dura to their confluence to form the basilar
artery

47. • Numerous muscular branches are given off as the artery ascends, with relatively large
ones passing posterior from V3 to supply the occipital triangle. They can anastomose
with occipital branches of the ECA.
• Spinal branches,
• pass into the spinal canal via the intervertebral foramina and
• supply vertebral bodies and extradural content of the canal and also of the dura and spinal cord,
reinforcing the anterior and posterior spinal arteries.
• In general branches include:
• V1:
• segmental cervical muscular and spinal branches
• V2:
• anterior meningeal artery, muscular and spinal branches
• V3:
• posterior meningeal artery
• V4:
• anterior and posterior spinal arteries (ASA and PSA), perforating branches to medulla, posterior
inferior cerebellar artery (PICA)

48. Supply
• ASA:
• upper cervical spinal cord, inferior medulla
• PSA:
• dorsal spinal cord to conus medullaris
• PICA:
• lateral medulla,
• tonsil,
• inferior vermis/cerebellum,
• choroid plexus of 4th ventricle
• penetrating branches: portion of the medulla, olives, inferior
cerebellar peduncle

51. Variation in anatomy
1. Asymmetry due to
a) vertebral arterial hypoplasia, absence or termination into PICA of one of the vertebral
arteries is very common
b) left dominant ~45% (range 42-50%)
c) right dominant ~30% (range 25-32%)
d) co-dominant ~25% (range 25-26%)
2. complete or partial vertebral artery duplication
3. vertebral artery fenestration
4. variable origin
1. aortic arch origin of left vertebral artery: incidence ~5% (range 3.1-8.3%)
2. second (not first) branch of subclavian artery
3. external carotid artery (rare) 8

52. PICA
• The “regular” PICA has:
• the most complex and variable course of the cerebellar arteries and
• divided into five segments. (p1 to p5 )
1. The anterior medullary segment
• in front of the medulla and
• extends from the origin to the level of the inferior olive.
2. The lateral medullary segment
• beside the medulla and
• extends from the inferior olive to the origin of the glossopharyngeal, vagus, and accessory nerves.
3. The tonsillomedullary or posterior medullary segment
• begins at the level of the nerves and loops below the inferior pole of the cerebellar tonsil and upward along the medial surface of
the tonsil toward the inferior medullary velum (caudal loop).
4. The telovelotonsillar or supratonsillar segment
• courses in the cleft between the tela choroidea and the inferior medullary velum rostrally and the superior pole of the cerebellar tonsil
caudally.
• It begins below the fastigium, where the PICA turns posteriorly over the medial side of the superior pole of the tonsil. This segment
forms the “cranial loop.” It sometimes passes posteriorly before reaching the superior pole of the tonsil, thus giving the cranial loop a
variable relationship to the fastigium.
• The junction of the posterior medullary and supratonsillar segments is called the choroidal point.
5. The Cortical segment; after a short distance distal to the apex of the cranial loop, the PICA continues posteriorly
downward in the retrotonsillar fissure,
• where it usually bifurcates into the
• tonsillohemispheric branch,
• which supplies the under aspect of the cerebellar hemisphere, and
• the inferior vermian branch, which lies on the lower aspect of the inferior vermis and forms a convex loop around the copula
pyramidis (pyramidal loop).

54. PICA ANERUSYM THROMBOSIS

55. PICA INFARCT

56. LATERAL MEDULLARY SYNDROME(WALLENBURG SYNDROME)
• caused by an acute ischemic infarct of the lateral medulla oblongata.
• most commonly due to :
• occlusion of the intracranial portion of the vertebral artery followed by PICA and its branches.
• This syndrome is characterised by:
• vestibulocerebellar symptoms: vertigo, falling towards the side of lesion, diplopia, and
multidirectional nystagmus (inferior cerebellar peduncle and vestibular nucleus)
• autonomic dysfunction: ipsilateral Horner's syndrome, hiccups
• sensory symptoms: initially abnormal stabbing pain over the ipsilateral face then loss of
pain and temperature sensation over the contralateral side of body (spinal trigeminal
nucleus involvement)
• ipsilateral bulbar muscle weakness: hoarseness, dysphonia, dysphagia, and dysarthria,
decreased gag reflex (nucleus ambiguus).

59. BASILAR ARTERY
• It artery arises from the confluence of the left and right vertebral
arteries :
• at the base of the pons
• in the central groove of the pons
• towards the midbrain within the pontine cistern.
• It travels within this groove from the lower pontine border adjacent to the
exit of the abducens nerve to the upper pontine border and the appearance
of the oculomotor nerve.
• It bifurcates at the upper pontine border.

61. • Before terminating at the upper pontine border where it divides into
the two posterior cerebral arteries, it provides several paired
branches:
• anterior inferior cerebellar artery (AICA)
• labyrinthine artery (variable origin; more commonly a branch of AICA)
• pontine arteries
• superior cerebellar artery (SCA)

62. BASILAR ARTERY ANEURYSM
• Less common than anterior circulation aneurysms, and rupture less frequently,
• but their critical location necessitates careful evaluation.
• basilar artery aneurysms can be both fusiform and saccular 2
•Radiographic features
• CT
• may present as a lobulated hyperattenuating structure anterior to the mid brain
• rupture of a basilar artery aneurysm is typically localised to the interpeduncular cistern, but may extend into
the suprasellar cistern
• CT angiography (CTA)
• provides better evaluation of the aneurysm and its relationship to other branches off the basilar artery
• Angiography
• better than CTA which is critical when considering intervention
• Treatment and prognosis
• Both unruptured and ruptured basilar artery aneurysms can be considered for clipping or
endovascular coiling.
• The type of treatment is tailored to the type of aneurysm (fusiform, saccular, branch, etc).
• If coiled, they require close follow-up to ensure complete occlusion, and may require re-treatment

64. BASILAR ARTERY OCCLUSION
• Acute occlusion of the basilar artery
• may cause brainstem or thalamic ischaemia or infarction.
• It is a true neuro-interventional emergency and, if not treated early, brainstem infarction results in
rapid deterioration in the level of consciousness and ultimately death.
• Epidemiology
• Occlusions of the posterior circulation arteries are related to a fifth of all strokes, and
• basilar artery occlusion is rare (~1% of all strokes)
• Clinical presentation
• Patients with acute occlusion of the basilar artery will present with sudden and dramatic
neurological impairment, the exact characteristics of which will depend on the site of occlusion:
 sudden death/loss of consciousness
 top of the basilar syndrome
 visual and oculomotor deficits
 behavioural abnormalities
 somnolence, hallucinations and dream-like behaviour
 motor dysfunction is often absent
 proximal and mid portions of the basilar artery (pons) can result in patients being 'locked in'
 complete loss of movement (quadriparesis and lower cranial dysfunction)
 preserved consciousness
 preserved ocular movements (often only vertical gaze)

65. TOP OF BASILAR SYNDROME
• Top of the basilar syndrome, (aka rostral brainstem infarction)
• occurs when there is thromboembolic occlusion of the top of the basilar artery.
• This results in bilateral thalamic ischaemia due to occlusion of perforator vessels.
• Clinically, top of the basilar syndrome is characterised by:
• visual and oculomotor deficits
• behavioural abnormalities
• somnolence, hallucinations and dreamlike behaviour
• motor dysfunction is often absent

66. BASILAR INFARCT

67. ANTERIOR INFERIOR CEREBELLAR ARTERY
• The anterior inferior cerebellar artery (AICA)
• It has a variable origin, course and supply, with up to 40%.
• The amount of tissue supplied by the AICA is variable (AICA-PICA dominance) but usually
includes:
• middle cerebellar peduncle
• inferolateral portion of the pons
• flocculus
• anteroinferior surface of the cerebellum
• Origin
• 99% of AICAs arise from the basilar artery, but where along the vessel is variable:
• 75% lower third
• 16% middle third
• 9% vertebrobasilar junction

68. AICA (Contd…)
• Branches :
• internal auditory branch (80% single, 20% double) passes into the IAM
• Rostro lateral branch
• Divided into Premeatal,Meatal and Post meatal segments
• Caudo medial branch supplies the biventral lobule.
• Before cross-sectional imaging, the AICA (along with venous displacement) was
used to identify posterior fossa intra- or extra-axial masses, especially at the CP
angle. Extra-axial masses (e.g. acoustic schwannomas or meningioma) would
displace the vessel whereas intra-axial masses tend not to.

72. AICA INFARCT

73. LABYRYNTHINE ARTERY • usually originates from the:
• AICA (~85%),
• basilar artery(~15%),
• vertebral artery (~5%) or
• even superior cerebellar artery.
• From its origin, it accompanies the
vestibulocochlear nerve and passes into
the internal acoustic meatus where it divides
into two branches:
1. anterior vestibular artery
2. common cochlear artery, which further
divides into
• proper cochlear artery
• vestibulocochlear artery: gives of a
vestibular ramus and a cochlear ramus

74. PONTINE ARTERY
• supply the pons and structures adjacent to the pons.
• Usually 3-5 paired arterial branches which are:
• located in the mid-basilar region between the anterior inferior cerebellar
artery and the superior cerebellar artery.
• APPLIED:
• PONTINE INFARCT
• Infarcts in the pons are typically focal.
• The pons is often poorly visualised on CT due to beam-hardening artifact from the petrous temporal bone.
Thus, MR imaging provides superior evaluation of the pons.

75. PONTINE SYNDROMES:
• Numerous clinical syndromes have been described due to pontine infarcts:
• Brissaud-Sicard syndrome
• facial colliculus syndrome
• Gasperini syndrome
• Gellé syndrome
• Grenet syndrome
• inferior medial pontine syndrome (Foville syndrome)
• lateral pontine syndrome (Marie-Foix syndrome)
• locked-in syndrome
• Millard-Gubler syndrome
• Raymond syndrome
• Raymond-Cestan syndrome

76. SUPERIOR CEREBELLAR ARTERY
• Origin:
• Arises from the distal basilar artery, just below the posterior cerebral artery (PCA)
• Supplies:
• It supplies the tentorial surface of the cerebellum, the upper brainstem, the deep cerebellar nuclei,
and the inferior colliculi.
• whole superior surface of the cerebellar hemispheres down to the great horizontal fissure
• superior vermis
• dentate nucleus
• most of the cerebellar white matter
• parts of the midbrain
• superior cerebellar peduncle
• middle cerebellar peduncle
• Variation:
• SCA is rarely absent, it is frequently duplicated:
• unilateral duplication: 28%
• bilateral duplication: 8%
• triplication: 2%

77. • Segments :
• Anterior ponto-mesencephalic
• Lateral Ponto mesencephalic (Ambient)
• Cerebello mesencephalic
• Cortical
• prepontine segment
• ambient segment
• quadrigeminal segment
• Branches :
• perforating branches
• pons
• midbrain
• inferior colliculus
• lateral (marginal) branch
• largest branch of the SCA
• usually arises from the ambient segment
• gives off hemispheric branches that course superiorly over the superior cerebellar hemisphere
• hemispheric branches
• supplies dentate nucleus
• superior vermis
• medial quadrigeminal lobule
• superior semilunar lobule
• superior vermian
• terminal branch(es) of the SCA
• anastomose with inferior vermian branches of the PICA

78. SCA INFARCT

83. POSTERIOR CEREBRAL ARTERY
• Embryologically the posterior cerebral artery arises as a branch of the ICA,
• but up to birth its most frequent origin is the basilar artery.
• The PCA is divided into four segments:
• P1
• extends from the basilar bifurcation to the site where the PCom joins the PCA.
• P2 extends from the PCom to the posterior aspect of the midbrain.
• P2 is further divided into
• P2A (anterior) from beginning of PCOM to Crus cerebri posterior margin (Within Crural cistern)
• P2P (posterior) segments. From crus cerebri to quadrigeminal cistern (within Ambient cistern)
• P3
• begins from lateral aspect of the quadrigeminal cistern and ends at the anterior limit of the anterior calcarine sulcus.
• P3 often divides into its (within Quadrigemninal cistern)
• major terminal branches, the calcarine and parieto-occipital arteries, before reaching the anterior limit of the anterior calcarine
sulcus.
• The point where the PCAs from each side are closer to each other is called the collicular or quadrigeminal point.
• It marks the posterior limit of the midbrain on angiograms
• The P4 segment is the cortical branches of the PCA

84. Branches of PCA
• Fetal origin of Pcom From PCA (Common variant 20-30%)
• choroidal branches (from P2)
• medial posterior choroidal arteries (P2A>P2P)
• lateral posterior choroidal arteries (P2P>P2A)
• perforators
• anterior thalamo perforator (from PCOM)
• posterior thalamo perforator (from P1)
• Thalamo geniculate perforator (from P2)
• peduncular perforator (from P2)
• circumflex (long and short)
• cortical branches (from P4)
• temporal branches
• anterior temporal artery
• posterior temporal artery
• lateral occipital artery
• anterior inferior temporal artery
• middle inferior temporal artery
• posterior inferior temporal artery
• medial occipital artery (from P3)
• calcarine artery
• parieto-occipital artery
• splenial artery (Posterior pericallosal artery)

86. PCA Supplies
• The posterior cerebral artery curls around the cerebral peduncle and passes
above the tentorium to supply
• the posteromedial surface of the temporal lobe and
• the occipital lobe.
• The visual cortex responsible for the contralateral field of vision lies in its territory.
• The macular part of the visual cortex often receives a dual blood supply from the PCA and
the MCA, which explains the "macular sparing" phenomenon in some patients following
a PCA infarct.

87. Partially thrombosed PCA aneurysm

90. • RIGHT PCA TERRITORY INFARCT
contralateral homonymous
hemianopia and
quadrantic visual field defects.
contralateral thalamic syndrome.

91. LEFT PCA INFARCT

92. INTERNAL CAROTID ARTERY
• It arises most frequently between C3 and C5 vertebral level,
• C3/4: 34.2%
• C4/5: 48.1%
• It first turns 90 degrees anteromedially
• within the carotid canal to run through the petrous temporal bone.
• It then proceeds to exit the carotid canal and turn 90 degrees superiorly within the
carotid sinus and
• finally another 90 degree turn anteriorly to travel along the roof of the cavernous
sinus, where it grooves the body of the sphenoid. Here the abducens nerve is
intimately related to the ICA on its lateral side.
• At the anterior end of the cavernous sinus,
• the ICA makes another 90 degree turn superiorly and then posteriorly to pass medial to the
anterior clinoid process.
• At this point it divides into the middle and anterior cerebral branches and gives off
other smaller branches, such as the anterior choroidal artery and the posterior
communicating artery.

95. Segments
•There are seven segments in the Bouthillier
classification:
1. cervical segment
2. petrous (horizontal) segment
3. lacerum segment
4. cavernous segment
5. clinoid segment
6. ophthalmic (supraclinoid) segment
7. communicating (terminal) segment

96. Branches
• C1: cervical segment, none
• C2: petrous (horizontal) segment
• caroticotympanic artery
• Vidian artery
• C3: lacerum segment, none
• C4: cavernous segment
• meningohypophyseal trunk (Posterior Trunk)
• inferolateral trunk
• C5: clinoid segment, none
• C6: ophthalmic (supraclinoid) segment
• ophthalmic artery
• superior hypophyseal artery
• C7: communicating segment
• posterior communicating artery
• anterior choroidal artery
• anterior cerebral artery
• middle cerebral artery

97. MENINGOHYPOPHYSEAL TRUNK
• It has three branches:
• inferior hypophyseal artery:
• to the pituitary gland, contributing to the "inferior hypophyseal arterial circle“
• marginal tentorial artery (Bernasconi-Casanari artery):
• to the meninges of the tentorium
• clival branches:
• to the meninges overlying the clivus

98. ICA STENOSIS
• The North American Symptomatic Carotid Endarterectomy Trial (NASCET)
formula for ICA stenosis calculation:
• % ICA stenosis = (1 - [narrowest ICA diameter/diameter normal distal cervical ICA]) x 100
• The European Carotid Surgery Trial (ECST) formula:
• % ICA stenosis = (1 - [diameter of the most stenotic part/estimated original diameter at the
site of the stenosis]) x 100