1. Blood supply to the brain
MBBS, Batch 17 Year II
Dr. Wai Wai Kyi

2. The brain
Composed of three parts:
▪ Cerebrum
▪ Cerebellum
▪ Brainstem
The cerebrum is
divided into four lobes:
♦ Frontal
♦ Parietal
♦ Temporal
♦ Occipital

3. Blood supply of the
brain
Two pairs of arteries, the carotid and vertebral.
■ The internal carotid
system, 80% of the
brain’s blood supply
(anterior circulation)
■ The vertebral basilar
system from
subclavian artery(20%)
(posterior circulation)
Anastomose in the
arterial circle of Willis.

4. Foramen lacerum
Carotid foramen
Internal carotid artery enters skull via carotid canal and emerging via that part of the foramen lacerum which is not occluded by cartilage
Vertebral artery enters skull via foramen magnum

5. Anterior clinoid
process

6. Internal carotid artery
■ One of the two terminal branchs of common carotid artery.
■ Begins in the neck at the upper border of thyroid cartilage.
Basilar a.
Internal
carotid a.

7. Internal carotid artery
Course in the cranial cavity
Enters the the base of skull & passes thro’ the carotid canal in the petrous portion of the temporal bone. its course here is extradural; emerging via that part of the foramen lacerum which is not occluded by cartilage.
Passes horizontally forward through cavernous sinus in an S-shaped curve (the carotid siphon).
Emerges on medial side of anterior clinoid process by piercing the dura & arachnoid mater.
Enters the subaracnoid space
Then it runs upwards to the anterior perforated substance where it terminates by dividing into the anterior and middle cerebral arteries.

8. Internal carotid artery

9. Brainstem (anteroinferior view)
Anterior perforated
substance
Posterior
perforated
substance

10. Parts of the internal carotid artery Cervical part – neck
Petrous part – carotid canal
Cavernous part – cavernous sinus
Cerebral part – base of the brain
Branches of the cerebral part
The internal carotid artery gives off no branches in the neck. Branches in the cerebral portion are as follows:
Ophthalmic
Posterior communicating
Anterior choroidal
Anterior cerebral
Middle cerebral
Terminal branches

13. Anterior cerebral artery

14. Middle cerebral
artery
Anterior cerebral
artery

15. Anterior cerebral artery Smaller terminal branch of the
internal carotid artery
Course:
Runs above the optic nerve to the medial surface of the frontal lobe of the cerebral hemisphere
Communicate with the ACA of opposite side by the anterior communicating artery
Curves round the genu of the corpus callosum
Enters anterior part of median longitudinal fissure;
curves backwards above the corpus callosum.
It terminates near the splenium by anastomosing with the posterior cerebral artery.
ACA
MCA
(Middle cerebral artery )
PCA

16. Anterior cerebral artery ▪ Supply - orbital surface of the frontal
Branches
Cortical branches
Central branches
Recurrent artery of Heubner
▪ Orbital, frontal, parietal
branches
▪ Supply - orbital surface of the frontal
lobe, all medial surface of the
cerebral cortex as far back as the
parietooccipital sulcus and adjacent
strip of the suprolateral surface of the
cerebral hemisphere.

17. Anterior cerebral artery Functional areas supplied
Upper part of primary motor area(4)
Upper part of somatosensory area (3,1,2)
Upper part of premotor area (6)
Upper part of prefrontal cortex (9,10,11,12)

18. Central branches of Anterior cerebral artery
Anteromedial group of central arteries
Joined the fellow of the opposite side by the anterior communicating artery.
Recurrent artery of Heubner
Pierces the anterior perforated substance
Supplies: basal ganglia, Internal capsule – anterior limb
Lentiform nucleus
▪ Globus pallidus
▪ Putamen

19. Middle cerebral artery

20. Middle cerebral artery
Larger terminal branch and main continuation of internal carotid
artery .Together the middle and anterior cerebral arteries are
referred to as the anterior circulation of the brain.
The middle cerebral artery is the artery most often occluded
in stroke.
Course
▪ Runs laterally in the stem of lateral sulcus between the orbital
and tentorial surfaces to the insula.
▪ Terminates on the insula
by dividing into branches.
Branches
Cortical branches
Central branches
(anterolateral group)

21. Middle cerebral artery
Cortical branches
Orbital, frontal, parietal and temporal branches supply the cerebral cortex
Supply
▪ Most of superolateral surface (except narrow strip along the
superomedial border from the frontal pole to parieto-occipital
sulcus, occipital lobe, Inferior temporal gyrus) & insular lobe.
▪ Lateral part of orbital surface
▪ Anterior part of tentorial surface 

22. Middle cerebral artery
Central branches (lateral striate /lenticulostriate arteries)
anterolateral group
Middle cerebral artery

23. Functional areas supplied (Middle cerebral artery)
Lower parts of
Primary motor area (area 4)
Premotor area (area 6)
Somatosensory area (area 3 1 2)
Prefrontal area (area 9,10,11,12)
Broca’s motor speech area (45,44)
Auditory area (41,42)
Supramarginal gyrus (40)
Angular gyrus (39)
Superior temporal gyrus (22)
Inferior parietal lobule

24. Frontal
Parietal Lobe
Temporal Lobe
Occipital Lobe

26. Distribution of middle cerebral artery

27. Anterior choroidal artery
Branch of internal carotid artery
Passes backward, enters inferior horn of lateral ventricle, and
ends in choroid plexus. It supplies:
Choroid plexus of the inferior horn of the lateral ventricle
Lateral geniculate body
Posterior limb & retrolentiform part of internal capsule
Mddle 3/5 of crus cerebri
Basal ganglia – globus pallidus

29. Anterior cerebral a
Middle cerebral a
Posterior cerebral a

30. Vertebral artery

31. Vertebral artery It has 4parts ▪ Originates from the subclavian artery & ascends towards the foramen transversarium of C6 vertebra ▪ Ascend through the transverse foramen of the upper six cervical vertebrae.(C6-C1) ▪ Emerges from the transverse foramen of the Atlas (C1) runs on the groove on the upper surface of the post. arch of the atlas and
pierces the atlanto-occipital membrane and enters the foramen magnum. C1 C2

32. ▪ Vertebral artery 4th part - Lies within cranium, the two arteries run on the anterior aspect of the medulla oblongata then unite at the lower border of the pons to form the basilar artery.
Branches of 4th part:
1. Meningeal Posterior spinal
2. Medullary Posterior inferior
3. Anterior spinal cerebellar
Posterior
arch of atlas
Posterior
atlanto-occipital
membrane
Pons

33. Basilar artery It’s formed by the union of 2 vertebral arteries Ascends in a groove on the anterior surface of the pons At the upper border of the pons/ ponto-midbrain junction, it’s divided into 2 posterior cerebral arteries. Branches from the basilar artery: 1. Anterior inferior cerebellar artery. 2.The labyrinthine artery. 3.The pontine branches (multiple vessels that penetrate the pons as paramedian, short circumferential, and long circumferential arteries). 4.The superior cerebellar arteries. 5. The basilar artery terminates by dividing into the posterior cerebral arteries at the upper border of the pons.

34. Inferior view anterior communicating a Internal carotid a Posterior
ACA
anterior
communicating a
Recurrent a of
Huebner.
Internal carotid a
Posterior
communicating a
MCA
Med. & Lat
lenticulostriate arteries
Superior
cerebellar a
Anterior choroidal a
Pontine arteries
PCA
Anterior inferior
cerebellar a
Labyrinthine a
Posterior inferior
cerebellar a
Basilar a
Vertebral a

35. Posterior cerebral artery

36. Posterior cerebral artery
Terminal branch of basilar artery
Course
Ascends beside the midbrain to
reach the splenium of the corpus callosum on the medial side of the cerebral hemisphere and terminates by dividing into branches
Connected to the internal carotid artery by the posterior communicating artery
Branches
Cortical
Central branches
Posterior choroidal artery

37. Posterior cerebral artery
Cortical branches:
▪ Inferior surfaces of temporal
lobe by temporal brs
▪ Medial surface of the occipital
lobe by calcrine brs
▪ Medial surface of the post
part of the parietal & part of
the occipital lobes by
parieto occipital brs
Functional area supplied:
▪ Visual area (17,18,19)

38. Posterior choroidal artery (branch of post. cerebral artery)
supply:
Choroid plexus of III ventricle
Choroid plexus of central part of lateral ventricle
Ventral part of thalamus
Fornix and superior colliculus of midbrain
Central branches of post. cerebral artery
Posteromedial group, posterolateral group
Many small perforating arteries arise from PCA to supply the
midbrain, thalamus, hypothalamus and medial and lateral
geniculate bodies.

39. Circle of Willis (circulus arteriosus)
Location
Lies in the interpeduncular fossa at the base of brain around optic chiasma, tuber cinereum and
mamillary bodies.
Formation
Anterior part
Anterior cerebral arteries (Rt & Lt)
Anterior communicating artery
Posterior part:
Basilar artery
Posterior cerebral arteries (Rt & Lt)
Lateral part
Internal carotid artery (Rt & Lt)
Posterior communicating arteries (Rt & Lt)L

41. Distribution of central arteries
Central arteries, arise from the arterial circle and proximal portion of the principal arteries, penetrate the substance of the brain and supply the deep structures.
Branches of the circle of Willis: central arteries, 6 groups
▪ Anteromedial group
▪ Posteromedial group
▪ 2 Anterolateral groups
▪ 2 Posterolateral groups

42. Branches of the circle of Willis

44. Anteromedial group of central arteries
Collectively they are referred to as the medial striate arteries.The
largest and most lateral of these to enter the brain is the medial
striate or recurrent artery of Huebner which arises from the
anterior cerebral artery.
Origin
Anterior cerebral and anterior communicating arteries
Distribution
Anterior part of hypothalamus
Head of caudate and lentiform nuclei
Anterior limb of the internal capsule

45. Anterolateral group of central arteries
They are also called the lateral striate or lenticulostriate
arteries.
Origin
Middle cerebral artery
Distribution
Internal capsule ( Genu, anterior & posterior limbs)
Caudate and lentiform nuclei
Lateral hypothalamus
The most common sites of spontaneous hemorrhage in
individuals with long-standing hypertension and is termed the
artery of cerebral hemorrhage. .

46. Posteromedial group of central arteries
Origin
Posterior cerebral artery (Thalamoperforate arterirs)
Posterior communicating arteries
Distribution
midbrain
Anterior and medial parts of thalamus
Posterior part of hypothalamus
Subthalamus
Posterolateral group of central arteries
Posterior cerebral artery (Thalamogeniculate arteries)
Posterior and lateral parts of thalamus
Geniculate bodies
Colliculi of midbrain and pineal gland

49. TGA- Thalamogeniculate a TPA -Thalamoperforate a
AChA -Anterior choroidal a
PCoA - Posterior communicating a
Middle cerebral artery
internal capsule
Post. cerebral a.
Thalamus
Caudate
nucleus
Ant. choroidal a
Mid brain
anterior cerebral artery

50. Internal capsule

51. Blood supply of the internal capsule
Anterior limb: lenticulostriate branches of middle cerebral artery (superior half) & recurrent artery of Heubner off of the anterior cerebral artery (inferior half)
Genu: lenticulostriate branches of middle cerebral artery
Posterior limb: lenticulostriate branches of middle cerebral artery (superior half) & anterior choroidal artery off of the internal carotid artery (inferior half)
Some degree of variation in the blood supply exists.
Retrolentiform + sublentiform parts = supplied by anterior choroidal

53. Blood Supply of medulla
Anterior and posterior spinal arteries
Vertebral arteries
PICA
Blood Supply of Pons
Paramedian branches of basilar artery (pontine arteries)
Short circumferential branches of basilar artery
Superior cerebellar artery and AICA
Blood Supply of Midbrain
Branches from basilar a.
Posterior cerebral artery and superior cerebellar artery (sup. & inf. colliculi)
Anterior choroidal a. and posterior communicating a.

54. The three major arteries of the cerebellum: the SCA, AICA, and PICA

56. Cerebral veins Veins of the brain have no muscular tissue in the wall and no valves Veins – Located in the subarachnoid space Venous sinuses – located between 2 layes of the dura

57. Cerebral vein is divided into:
1.Superficial cerebral veins
Superior cerebral veins
Inferior cerebral veins
Superficial middle cerebral
vein
2. Deep cerebral veins
Internal cerebral veins
Basal vein (Rosenthal)
Great cerebral vein (of Galen)
Superficial veins
Drain the cortex and the more
superficial hemispheric white
mater mainly into the superior
sagittal and cavernous sinuses.
Deep or internal veins
Drain the deep hemispheric
white mater, basal ganglia,
thalamus, internal capsule
and choroid plexus into the 2
internal cerebral veins which
unite to form the great
cerebral vein.
Superficial and deep veins of
the brain drain into the dural
venous sinuses (which in turn
drain into the internal jugular
veins).

58. Superior Anastomotic Vein - connect the superficial middle cerebral vein with the superior sagittal sinus
Inferior Anastomotic Vein - connects the superficial middle cerebral vein with the transverse sinus. .

59. Internal cerebral vein
Situated in the tela choroidea of third ventricle, in the roof of third ventricle.
Formation: At the interventricular foramen by the union of thalamostriate vein and choroidal veins.
Termination: Below the splenium two Internal cerebral vein joins to form the great cerebral vein.
Great cerebral vein (or vein of Galen)
Situated below the spenium, in the cystern of great cerebral vein.
Formation: By the union of two internal cerebral veins.
Termination: Joins the inferior sagittal sinus to form straight sinus.
Tributaries: Right and left basal veins

61. Course: Runs posteriorly around the midbrain
Basal vein:
Formation: At the anterior perforated substance by the union of anterior cerebral vein, deep middle cerebral and striate veins
Course: Runs posteriorly around the midbrain
Termination: Below the splenium by joining the great cerebral vein
There are numerous venous connections between cerebral veins and dural sinuses and venous systems of the meninges, skull, scalp and nasal sinuses so facilitating propagation of thrombus or spread of infection between these vessels.

62. Blood supply to spinal cord Arterial supply
▪ Posterior spinal arteries
2 branches – arise directly or indirectly from vertebral arteries
▪ Anterior Spinal artery
1 branch - from vertebral arteries
▪ Spinal arteries are reinforced by
radicular arteries. Arteria radicularis
magna (artery of Adamkiewicz) is the
largest of the anterior radicular arteries
and major source of blood supply to
lower thoracic and upper lumbar spinal
cord levels.
Radicular arteries
Are branches from segmental arteries:
Ascending cervical a., Deep cervical a.
Posterior Intercostal a. , Lumbar a. , Sacral a.

64. Spinal veins
Spinal veins form plexuses anteriorly and posteriorly
On each side the spinal veins are double, straddling the posterior nerve roots
All of them drain into
vertebral veins in the neck,
azygos veins in the thorax,
lumbar veins in the lumbar region,
lateral sacral veins in the sacral region through intervertebral foramina.

65. Anterior spinal arteries supply 2/3 anterior aspect of spinal cord
Posterior spinal arteries supply 1/3 posterior aspect of spinal cord

66. Any Questions ?
THANK YOU