Blood Supply Of Brain

1. Dr. Fatima Hamza
Blood supply of brain

2. Arteries of brain
•The brain is supplied by two
sets of arteries:
(1) internal Carotid
(2) vertebrobasilar arteries

5. Internal Carotid Arteries
•Arises from common carotid
artery in the neck at the level of
C4 vertebra
•Carotid sinus - a small swelling
present at point of origin of
internal carotid artery

6. The course of the internal carotid artery
• 1. Cervical part: origin till it enters the
carotid canal with in carotid sheath
• 2. Petrous part: carotid canal in the
petrous temporal bone.
• 3. Cavernous part: enters the skull
through foramen lacerum.
• 4. Cerebral part: pierces the dura
mater of the roof of the cavernous
sinus and enters the subarachnoid
space.

8. Branches
1. Opthalmic artery- orbit and
its contents
2. Posterior communicating
artery - anastomoses with the
posterior cerebral artery, a
branch of the basilar artery

9. 3. Choroidal artery - forms the
choroid plexus of the inferior horn
of lateral ventricle
4. Anterior cerebral artery – medial
surface of cerebrum and upper
strip of the superolateral
surface except occipital lobe.
5. Middle cerebral artery –
superolateral surface of
cerebrum

10. Vertebrobasilar Arteries
•branch of the first part of the
subclavian artery in the neck

11. Course of vertebral Artery
•Cervical part: origin till it enters
the foramen transversarium of
C6 vertebra. Here,
•2. Vertebral part: the foramina
transversaria of upper six
cervical vertebrae.
•3. Suboccipital part: lying in the
suboccipital triangle.

13. •Cerebral part: enters the
cranial cavity by passing
through the foramen
magnum pierces the dura
mater and enter the
subarachnoid space lying in
the subarachnoid space
lateral to the medulla
oblongata.

15. Branches of the
Cerebral Part
1. Anterior spinal artery:
medulla oblongata and spinal
cord.
2. Posterior spinal artery:
spinal cord.
3. Posterior inferior cerebellar
artery: medulla oblongata,
cerebellum and the choroid
plexus of the fourth ventricle.
4. Medullary branches:
medulla oblongata.
5. Meningeal branches:
meninges of the posterior
cranial fossa.

16. Basilar Artery
•The basilar artery, formed
by the union of the two
vertebral arteries
•ascends in a groove on the
anterior surface of the pons
•upper border of the pons, it
divides into the two
posterior cerebral arteries

17. Branches of basilar artery
1. Pontine - the substance of
the pons
2. labyrinthine artery internal
ear
3. anterior inferior cerebellar
anterior and inferior parts of
the cerebellum
4. Superior cerebellar the
superior surface of the
cerebellum, the pons, the
pineal gland, and the
superior medullary velum.

18. • The posterior cerebral
artery supplies the visual
cortex.
• Central branches
thalamus and the
lentiform nucleus as well
as the midbrain, the
pineal, and themedial
geniculate bodies
• Choroidal branch
lateral ventricle choroid
plexus of the third
ventricle

19. Circle of willis
•It is formed by the anastomosis
between the two internal carotid
arteries and the two vertebral
arteries
•Location - interpeduncular fossa

20. Arteries of circle of Willis
1. The anterior communicating
2. anterior cerebral
3. internal carotid
4. posterior communicating
5. Posterior cerebral
6. basilar arteries

22. Arteries to Specific Brain Areas
•The corpus striatum and
the internal capsule are
•the medial and lateral
striate central branches of
the middle cerebral artery
the central branches of the
anterior cerebral artery
supply the remainder of
these structures

23. • The thalamus -- the posterior
communicating, basilar,and
posterior cerebral arteries
• The midbrain -- posterior
cerebral, superior cerebellar,
and basilar arteries
• The pons -- the basilar and
the anterior, inferior, and
superior cerebellar arteries

24. • The medulla oblongata
--vertebral, anterior and
posterior spinal, posterior
inferior cerebellar, and
basilar arteries.
• The cerebellum -- is
supplied by the superior
cerebellar, anterior inferior
cerebellar, and posterior
inferior cerebellar arteries.

25. Veins of brain
•The veins of the brain have
no muscular tissue in their
very thin walls, and they
possess no valves.
•They emerge from the brain
and lie in the subarachnoid
space.

26. External Cerebral Veins
•The superior cerebral veins
-- superior sagittal sinus
•The superficial middle
cerebral vein -- cavernous
sinus
•The deep middle cerebral
vein
•joined by the anterior
cerebral and striate veins to
form
•the basal vein drains into

27. Internal Cerebral Veins
•two internal cerebral veins,
and they are formed by the
union of the thalamostriate
vein and the choroid vein.
•These veins unite to form
great cerebral vein that drains
into straight sinus

28. • The midbrain is drained by veins
that open into the basal or great
cerebral veins.
• The pons is drained by veins that
open into the basal vein, cerebellar
veins, or neighboring venous
sinuses.
• The medulla oblongata is drained
by veins that open into the spinal
veins and neighboring venous
sinuses.
• The cerebellum is drained by
veins that empty into the great
cerebral vein or adjacent venous
sinuses

30. Arteries of the Spinal Cord
•The spinal cord receives its
arterial supply from three small
arteries:
1. two posterior spinal arteries
2. anterior spinal artery

31. Segmental Arteries
segmentally arranged arteries that
arise from arteries outside the
vertebral column and enter the
vertebral canal through the
intervertebral foramina

32. Blood Brain Barrier
•Capillaries in the brain lack
fenestrations and contain
tight junctions, due to these
characteristics only selective
transport of substances is
possible across the
endothelitial cells

33. Blood brain barrier
•The blood-brain barrier lets
some substances, such as
water, oxygen, carbon
dioxide, and general
anesthetics, pass into the
brain. It also keeps out
bacteria and other
substances, such as many
anticancer drugs. Also called
BBB.

34. BBB FORMING STRUCTURES
•Endothelial cells
•Basement membrane
•Astrocytes

35. Clinical significance
•Ischemia
•Hemorrhage
•Aneurysms

36. Clinical Anatomy
•Cerebral Ischemia
•Unconsciousness occurs in 5 to
10 seconds if the blood flow to
the brain is completely cut off.
Irreversible brain damage with
death of nervous tissue rapidly
follows complete arrest of
cerebral blood flow.

37. Interruption of Cerebral Circulation
•Vascular lesions of the
brain are extremely
common, and the
resulting neurologic
defect will depend on the
size of the artery
occluded, the state of the
collateral circulation, and
the area of the brain
involved

38. Anterior cerebral artery

39. Middle cerebral Artery

43. Impairment of Cerebral Blood Flow

45. Hemorrhage
•Intracranial hemorrhage can
result from trauma or cerebral
vascular lesions.
•Four varieties are considered: (1)
epidural,(2) subdural, (3)
subarachnoid, and (4) cerebral.
Epidural and subdural
hemorrhage are described on
page

46. Subarachnoid Hemorrhage
results from leakage or rupture
of a congenital aneurysm on
the cerebral arterial circle
Symptoms - severe headache,
stiffness of the neck, and loss
of consciousness. The
diagnosis is established by the
use of computed tomography
(CT).

47. Cerebral hemorrhage
•hemiplegia on the opposite
side of the body.
•immediately loses
consciousness,
•paralysis is evident when
consciousness is regained.
•Hemorrhage may also occur
into the pons and cerebellum.

48. Thank You