The document discusses the arterial supply of the brain. It describes the major arteries - the vertebral arteries, basilar artery, internal carotid arteries, anterior cerebral artery, middle cerebral artery, and posterior cerebral artery. These arteries form anastomoses around the circle of Willis at the base of the brain to provide a continuous blood supply to the brain through both the carotid and vertebral systems. Disruptions to this arterial network can impair blood flow and oxygen delivery to the brain.

1. By:
Jekadeshnaidu Panirselvam BPT
MSc Human Anatomy
Faculty of Medicine,
AIMST University
ARTERIAL SUPPLY OF BRAIN

2. Contents
 Introduction
 Vertebral Artery
 Basilar Artery and Branches
 Carotid Artery
 Cerebral Arteries
 Anterior Cerebral Artery
 Middle Cerebral Artery
 Arterial Supply of the Different Surfaces of the Cerebral
Hemisphere
 Circle of Willis (Circulus Arteriosus)
 Clinical Aspects
 References

3. Introduction
 Brain is composed of:
 Cerebrum
 Cerebellum
 Brainstem
 Cerebrum is again divided in 4 lobes:
 Frontal
 Occipital
 Temporal
 Parietal
 Continuous blood supply to the brain is of utmost
importance due to its high metabolic demands for
oxygen and glucose.

4. Introduction
• The consciousness is lost
within 10 seconds of
cessation of blood flow,
and if the state continues,
an irreversible brain
damage starts to occur at
about 4 minutes and is
completed within 10
minutes
• The brain is supplied by the
paired internal carotid and
vertebral arteries via an
extensive system of
branches, thus the brain is 2
systems of arteries:-
• Vertebral system
• Carotid system

5. Vertebral Artery
 Is a branch of subclavian artery, ascends in the
foramina transversaria of upper 6 cervical vertebra (1st
part)
 At the base of skull, it winds backwards and medially
around the lateral mass of atlas and pierces posterior
atlanto-occipital membrane (2nd part)
 Enters cranial fossa through foramen magnum and
runs anterolateral aspect of medulla (3rd part)
 It then converge and unite at lower border of pons to
from Basillar artery (4th part)

6. Vertebral Artery
 Anterior spinal artery
 Small branch arising near the termination of vertebral
artery. It descends in front of medulla and unites with its
fellow opposite side at the level of lower end of the olive
to form single median trunk
 Posterior spinal artery
 Arises from vertebral or sometimes from posterior inferior
cerebellar artery. Passes downwards on the posterior
surface of spinal cord; after dividing, one on medial and
one on lateral side of dorsal roots of spinal nerves
 Posterior inferior cerebellar artery
 Largest branch, arises near the lower end of olive, winds
backwards around medulla oblongata and then ascends
to the pontomedullary juntion
Branches of 4th part of Vertebral artery

7. Vertebral Artery
 Meningeal branches
 Small and supply the dura mater of posterior
cranial fossa
 Medullary arteries
 Supplies medulla oblongata
Branches of 4th part of Vertebral artery

8. Basilar Artery
 Formed by the union of 2 Vertebral
arteries at lower border of pons
 Ascends in the basilar sulcus on the
ventral aspect of pons and terminates
at upper border of pons and divides
into:
 Right and Left posterior cerebral
arteries
 Branches of basilar artery:
 Pontine branches
 Anterior inferior cerebral artery
 Labyrinthine artery
 Superior cerebral artery
 Posterior cerebral artery

9. Branches of Basilar Artery
 Pontine Branches
 Numerous short slender paramedian vessels – piercers
pons and supplies it
 Anterior inferior cerebral artery
 Arises close to the lower border of pons and runs
backwards and laterally to the 7th and 8th cranial nerves
 Supplies the internal acoustic meatus and
anterolateral portion of inferior surface of cerebellum
 Superior cerebral artery
 Arises close to superior border of pons, runs laterally
below the oculomotor nerve.
 Winds around cerebral peduncle below trochlear nerve
and supplies superior surface of the cerebellum

10. Branches of Basilar Artery
 Labyrinthine artery
 Long slender branch which arises from basilar
artery or from anterior inferior cerebral artery
 Accompanies vestibulocochlear nerve and
enters internal auditory meatus and supplies
 Posterior cerebral artery
 Passes laterally parallel to the superior cerebral
artery, curves around midbrain to reach the
medial surface of cerebral hemisphere – under
splenium of corpus callosum
 Each artery provides 3 sets of branches:-
 Postero-lateral striate branch
 Posterior choroid artery

11. Posterior Cerebral Artery - Branches
 Postero-lateral striate branches – Supplies caudal
part of the thalamus including geniculate body and
lateral thalamic nuclei
 Posterior choroid artery – Arises beneath splenium,
runs forward through transverse fissure and provides
branches to the choroid plexus of lateral ventricle, third
ventricle and posterior part of thalamus
 Cortical branches – Divide in temporal and internal
occipital arteries.
 Temporal branch supplies temporal lobe except
temporal pole
 Internal occipital artery subdivides into parieto-occipital
and calcarine branches and supplies cuneus and pre-
cuneus.
 Calcarine artery is important because it supplies primary

12. CarotidSystem– Internal CarotidArtery
 Terminal branch of common carotid artery, transverse
the carotid canal in the base of skull and enters
middle cranial fossa
 Runs forward along the floor and medial wall of the
cavernous sinus and then turns upwards on medial
side of clinoid process
 The artery pierces the dural roof of cavernous sinus
and arachnoid mater to enter subarachnoid space.
 Runs upwards and lie besides optic chiasma, just
underneath the anterior perforated substance of the
brain and terminates by dividing into 2 branches:
 Middle Cerebral artery
 Anterior Cerebral artery

13. Branches of Internal CarotidArtery – Cerebral part
 Ophthalmic artery
 Arises from ventral convexity of carotid siphon and enters
optic canal to reach orbital cavity – supply the structures
of orbit and eyeball
 Posterior communicating artery
 Arises close to the termination of internal carotid artery.
 Runs backwards and anastomoses with the proximal part
of posterior cerebral artery
 Anterior choroidal artery
 Long slender branch, arises distal to the origin of
posterior communicating artery
 Runs backwards above and along optic tract to enter the
inferior horn of the lateral ventricle and end in choroid

14. Branches of Internal CarotidArtery – Cerebral part
 Anterior cerebral artery
 Smaller terminal branch of the
internal carotid artery
 Runs forward and medially
above optic nerve and gets
joined with by a short
transverse anterior
communicating artery.
 Curves around the genu of
corpus callosum
 Continues along the upper
surface of corpus callosum as
pericallosal artery and gives off
a large branch
 Anastomose with posterior
• Recurrent artery of
Heubner
• Arises proximal to
the communicating
artery, recurs
backwards and
laterally, penetrates
anterior perforated
substances and
supplies ventral part
of caudate nucleus,
putamen, anterior
limb of genu of the
internal capsule.

15. Anterior Cerebral Artery
 Calloso-marginal artery is large branch, extends
backward along sulcus cinguli and supplies paracentral
lobule
 The areas distributed by cortical branches of ACA
include:
 Medial part of orbital surface
 Corpus callosum
 Medial parts of frontal and parietal lobe up to parieto-
occipital sulcus, and a strip of cortex on the supero-
medial border of the hemisphere

16. Branches of Internal CarotidArtery – Cerebral part
 Middle cerebral artery
 Larger terminal branch of the internal carotid artery
 Direct continuation of internal carotid artery and carries
about 30% of carotid blood flow
 Runs laterally in the stem of the lateral sulcus and turns
backwards and upwards in the posterior ramus of the
lateral sulcus
 Breaks up into frontal, parietal and temporal branches
which emerge from lateral sulcus and run towards the
area of their supply.
 Gives off central and cortical branches

17. Middle Cerebral Artery
 Cortical Branches:
 Pre Rolandic and Rolandic branches
 Anterior and posterior parietal arteries
 Posterior temporal artery
 Angular artery
 Central Branches:
 Lenticulo-striate branches – Pierce the anterior perforated
substance and arranged in medial and lateral striate
branches
 Medial striate ascends through the lentiform nucleus –
supply caudate nucleus and internal capsule
 Lateral striate ascends along external capsule and the
turn medially through lentiform nucleus to supply caudate
nucleus.
 * The striate arteries are vulnerable to rupture in the
presence of high blood pressure

18. Distribution of Middle Cerebral Artery

20. Circle of Willis
 Circulus anteriosus of Willis forms a polygonal
anastomotic channel between internal carotid artery
and 2 vertebral arteries
 Situated at the base of brain around the optic chiasma
and other structures of interpendicular fossa
 The circle is formed by:-
 In front – Anterior communicating artery
 Antero-laterally - 2 Anterior cerebral arteries
 Laterally – Proximal segments of internal carotid arteries
 Postero-laterally – 2 Posterior communicating arteries
 Behind – Proximal segments of both Posterior cerebral
arteries

21. Circle of Willis - Branches
 Provides a number of central branches which
penetrate the base of brain and supply the
diencephalon, corpus striatum and internal capsule
 The branches are as follow:-
1. Antero-medial branches
2. Paired antero-lateral branches
3. Postero-medial branches
4. Paired postero-lateral branches
* Central branches of arterial supply of the cerebrum

22. Branches of Circle of Willis
 Antero-medial Branches
Derived from anterior communicating and anterior
cerebral arteries and pierces the anterior perforated
substance.
Distribute to pre-optic and supra-optic region of anterior
hypothalamus
 Paired Antero-lateral branches
Derived from medial striate branch of anterior
cerebral and lateral striate of branches of medial
cerebral arteries.
Distribute to corpus striatum and most of internal
capsule
 Postero-medial branches
Derived from posterior communicating and posterior

23. Branches of Circle of Willis
 Paired postero-lateral branches
Derived from posterior cerebral arteries
Distribute to caudal part of thalamus, geniculate bodies
and lateral thalamic nuclei

24. Arterial Supply of the Cerebrum
 Supplied by 3 pairs of arteries; Anterior,
middle and posterior
 Gives 3 branches; Cortical, central and
choroidal
 Cortical branches
Supply outer portion of the cerebrum and
vessels freely anastomose and from a
network in pia mater at cerebral cortex.
Once they enter the cortex, the become end
arteries:
1. Short, which confine themselves in the cortex

25.  Choroidal branches
Form a network of capillaries which project into the
ventricles after invaginating layers of pia mater and
ependyma forming choroid plexus
Anterior choroidal artery – Arises from internal carotid,
runs posteriorly near optic tract and crosses the uncus
to enter choroidal plexus in the inferior horn of lateral
ventricle
Posterior choroidal artery – Arises from posterior
cerebral artery, encircles the midbrain to enter choroidal
plexus of third and lateral ventricle through transverse
fissure.
Arterial Supply of the Cerebrum

26. Arterial Supply of the Different Surfaces of the Cerebral Hemisphere
 Superolateral Surface
 2/3 supplied by middle cerebral artery – Primary
motor and sensory areas, and frontal eyefield
 A narrow strip of cerebral cortex adjoining
superomedial border up to the parieto-occipital
sulcus is supplied by Anterior cerebral artery
 A narrow strip along the lower border of temporal
lobe and occipital lobe supplied by Posterior
cerebral artery.

27.  Medial Surface
 Most of anterior 2/3 is supplied by anterior
cerebral artery – Supplies motor and sensory areas
(paracentral lobule) concerned with perineum, leg
and foot
 Temporal lobe is supplied Middle cerebral artery
 Occipital lobe is supplied by Posterior cerebral
artery – Visual cortex
Arterial Supply of the Different Surfaces of the Cerebral Hemisphere

28.  Inferior Surface
 Most of inferior surface except the temporal pole is
supplied by Posterior cerebral artery
 Lateral part of orbital surface of the frontal lobe and
temporal pole of temporal lobe – Middle cerebral artery
 Medial part of the orbital surface of the frontal lobe –
Anterior cerebral artery
Arterial Supply of the Different Surfaces of the Cerebral Hemisphere

30. Congenital cerebral aneurysms
 Occurs at site where
2 arteries join to form
circle of Willis
 Also known as Berry
aneurysms
 Pathologic focal
dilatations of the
cerebrovasculature
that are prone to
rupture
 Happens due to
congenital deficiency
of tunica media in
the arterial wall

31.  Results from rupture of
congenital berry aneurysms
in the interpendicular cisten.
 Extravasation of blood into
the subarachnoid space
between the pia and
arachnoid membranes
 Caused also by head
trauma
 Symptoms:
 Sudden onset of severe
headache
 Photophobia and visual
changes
Subarachnoid haeMORRHAGE

32. Occlusion of Cerebral Arteries
 Anterior cerebral artery
 Contralateral hemiparesis
and hemianaesthesia
involving mainly leg and
foot – Upper parts of
primary motor and sensory
areas
 Agnosia – Due to
involvement of superior
parietal lobule
 Apathy and personality
changes due to
involvement of part of
frontal lobe
• Middle cerebral artery
• Contralateral hemiplegia
and hemianaesthesia
mainly face and arm –
Primary motor arid sensory
areas
• Aphasia is left dominant
hemisphere involved –
motor and sensory speech
area
• Contralateral homonymous
hemianopia – optic
radiation

33.  Posterior cerebral artery
 Contralateral homonymous hemianopia – visual cortex
 Macular vision is spared due to it is represented in the occipital
pole which receives collateral supply from middle cerebral
artery.
Occlusion of Cerebral Arteries

34. ACA
MCA
PCA

35. Cerebral Vascular Accident
 ‘A stroke is caused by
the interruption of the
blood supply to the brain,
usually because a blood
vessel bursts or is
blocked by a clot. This
cuts off the supply of
oxygen and nutrients,
causing damage to the
brain tissue.’ (WHO
definition)
 The effects depends on
which area of the brain is
injured and how severely

36. Ischemic Hemorrhagic
 Arteries supplying the
brain become narrowed
or blocked, causing
severely reduced blood
flow.
 Approx. 80% of stroke
cases
 Subdivide into:
 Thrombotic Infarct
(approx. 10-15% of
cases)
 Embolic Infarct
 Occurs when a
blood vessel in your
brain leaks or
ruptures.
 Subdivided into:
 Intracerebral
hemorrhage
 Subarachnoid
hemorrhage

37. Cerebral Angiography
 Is a radiological technique to visualize the vessels of
the brain.
 A radiopaque solution will be into one of the major
arteries supplying the brain and serial radiographs of
skull will be taken at 1 second intervals.
 Used to identify vascular malformations and
aneurysms.
 Injection into common carotid – Anterior and middle
cerebral arteries
 Injection into vertebral artery – Vertebral, basilar and
posterior cerebral arteries.

38. References
• Clinical Neuroanatomy – Vishram Singh 2nd Editon
• B D Chaurasia Human Anatomy Vol 3 (5th Edition)
• Essentials of Human Anatomy – A.K Datta (4th
Edition)
• Drake. R.L, Volgl. A.W, and Mitchell. A.W.M. (2010)
Gray’s Anatomy for Students, 2nd edn. Canada;
Churchill Livingstone.
• Standring, S. (2008) Gray’s Anatomy: The
Anatomical Basis of Clinical Practice, 40th edn.
Churchill Livingstone Elsevier; Spain.
• World Health Organisation (2014) ‘Stroke,
Cerebrovascular accident’, Available at:
http://www.who.int/topics/cerebrovascular_accident/e
n/

39. Questions??
?