5. Vertebrobasilar System
• Upper cervical spinal cord
• Brainstem and Cerebellum,
• most of the Thalamus
• Hypothalamus
• Posterior Medial Parietal lobes
• Medial & Inferior temporal lobes
• Occipital lobes
• Splenium of Corpus Callosum
6. Vertebral
Artery
Branches of 1st part of
subclavian artery
Ascends neck in the
transverse process of
upper six cervical
vertebra
Enters skull through
foramen magnum and
enters subarachnoid
space
Passes medially on
medulla oblongata
At the lower border of
pons joins vessel of the
opposite side to form
basilar artery
8. Basilar
Artery
•Formed by union of
two vertebral arteries
•Ascends in a groove
on the anterior
surface of pons
•At the upper border
of pons divides into
two PCA
9. Branches
Pontine Arteries: supplies
pons
Labyrinthine Artery: supplies
internal ear
Anterior Inferior Cerebellar
Artery: supplies anterior and
inferior part of cerebellum
Superior Cerebellar Artery:
supplies superior surface of
cerebellum, pons, pineal
gland, superior medullary
velum
Posterior Cerebral Artery:
10. Posterior
Cerebral Artery
•At the level of the
midbrain the basilar
artery bifurcates to
form the two posterior
cerebral arteries.
•Curves laterally and
Backwards
• Around the
Midbrain.
•Here It is joined by
posterior
• Communicating
branch of ICA to form
the circle of Willis.
11. PICA
Largest branch of
Vertebral Artery
Supply
• Sup surface of
Vermis and
central nuclei of
cerebellum
• Medulla
oblongata
• Choroid plexus
of fourth
ventricle
13. Blood Supply of the Spinal Cord
The spinal cord receives its arterial supply
from three small arteries:
• Two posterior spinal arteries
• One anterior spinal artery
• Longitudinally running arteries are reinforced by small
segmentally arranged arteries that arise from arteries
outside the vertebral column and enter the vertebral
canal through the intervertebral foramina. These
vessels anastomose on the surface of the cord and
send branches into the substance of the white and gray
matter.
14.
15. Anterior Spinal Artery
• The anterior spinal artery is formed by the
union of two arteries, each of which arises
from the vertebral artery inside the skull. The
anterior spinal artery then descends on the
anterior surface of the spinal cord within the
anterior median fissure. Branches from the
anterior spinal artery enter the substance of
the cord and supply the anterior two-thirds of
the spinal cord.
16. Posterior Spinal Arteries
• The posterior spinal arteries arise either
directly from the vertebral arteries inside the
skull or indirectly from the posterior inferior
cerebellar arteries. Each artery descends on
the anterior surface of the spinal cord close to
the posterior nerve roots and gives off
branches that enter the substance of the cord.
The posterior spinal arteries supply the
posterior on third of the spinal cord.
19. Posterior Cerebral Artery
• Central branches: Supplies
- part of the thalamus and
- the lentiform nucleus and
- the mid brain
- the pineal gland
- the medial geniculate bodies
20. Contd…
• Cortical branches:
1. Posterior branches to the lateral and medial
surfaces of occipital lobe, Optic radiations and visual
cortex & Splenium of the corpus callosum
2. Anterior branches to the inferolateral and
medial.surfaces of temporal lobe, Hippocampal
formation and the posterior fornix ( new declarative
memories)
3. Choroidal branches: supplies choroid plexus of
lateral and third ventricle
23. Internal Carotid
Artery (ICA)
•- begins at the
bifurcation of CCA
• - ascends neck
• - perforates base
of the skull by passing
through the carotid
canal of temporal bone
• - runs horizontally
forward through
cavernous sinus
• - enters into sub-
arachnoid space
• - turns posteriorly
to the medial end of
lateral sulcus to divide
into ACA and MCA
24. Branches
Choroidal Artery-supplies-
1) crus cerebri
2) lateral geniculate
body
3) optic tract
4) parts of internal capsule
Ophthalmic Artery-
supplies-
1) eye
2) orbital structures
3) frontal area of scalp
4) ethmoid and frontal sinuses
5) dorsum of nose
Posterior
Communicating
Anterior Cerebral
Artery-
Middle cerebral Artery-
25. Anterior Cerebral
Artery
Smaller Terminal Branch of
ICA.
• Runs Superior to optic
nerve and
enter the longitudinal
fissure of
the cerebrum.
• Here it is Joined to anterior
cerebral artery of opposite
side
by A. com artery
• It then Curves backward
over the
Corpus Callosum &
anastomose
with PCA
27. ACA
• Penetrating Branches
(Central Branches)
1) Part of Lentiform
nucleus
2) Caudate nucleus
3) Part of Internal Capsule
• Cortical Branches
1) Orbital and medial
surfaces of frontal and
parietal lobes up to
parieto- occipital
sulcus.
2) Strip of Cortex about 1
inch
3) Para central Lobule( Area
below Knee and
Control of Anal &
bladder Sphincter)
28.
29. Middle cerebral
Artery
Largest Branch of ICA. Runs
in the lateral Sulcus
The Initial part of the MCA
is called the Stem
As it Passes Laterally, the
Stem gives off series of 6-
12 small diameter
Penetrating Vessels
(lenticulostriate arteries).
Then It Passes to the
Lateral Surface of the
Cerebral Hemisphere and
Gives of Cortical Superior
and Inferior Branch.
32. MCA
• Superior Division:
- Contra lateral
hemiplegia with
significant inv of the
upper limb
- Deviation of Eye
towards the side of the
lesion
- Broca’s Aphasia or
Motor Aphasia
• Inferior Division:
- Wernicke’s or sensory
Aphasia
- Superior quadrantic
hemianopia
- Visual neglect
- Apraxia (refers to the
inability to perform a
previously learned task
despite preserved
strength, vision, and
coordination)
35. Circle of
Willis
Lies in the
interpeduncular fossa at
the base of the brain
Formed by anastomosis
between two ICA and
two vertebral arteries
The A.com artery, ACA,
PCA, P.com artery and
Basilar artery contribute
Allows blood to be
distributed to any part
of both cerebral
hemispheres.
36.
37. Blood Supply of
Brain stem
The brain stem
(Medulla, Pons &
Midbrain) receives
its blood supply
from the
vertebrobasilar
system.
Vertebral & Basilar
artery are the two
main arteires of
the brainstem.
38. Cont…
1. Para median
branches: Supplies
Medial parts of the
Brainstem. These are
long slender penetrating
branch. They are at risk
for hypertensive
damage, particularly in
the Pons.
2. Circumferential
branches: Dorsolateral
parts of the brainstem
are supplied by direct
circumferential
branches of either
vertebral or basilar
arteries
39. Blood Supply of
Medulla
1. Anterior spinal artery:
supplies to the
paramedian region of the
caudal medulla.
2. Posterior spinal artery:
supplies rostral areas,
including the gracile and
cuneate fasiculi and
nuclei & dorsal areas of
the inferior cerebellar
peduncle.
3. Vertebral artery: bulbar
branches supply areas of
both the caudal and
rostral medulla.
4. Posterior inferior
cerebellar artery:
supplies lateral medullary
areas.
40. Blood Supply to
the Pons
1. The Basilar artery-
Contributions of this main
artery can be subdivided
a. Paramedian
branches: to medial Pontine
region
b. Short
circumferential branches:
supply anterolateral
pons
c. Long circumferential
branches: run over the
anterior
surface of the Pons to
anastomose with AICA.
2. Some reinforcing
contributions by the anterior
inferior cerebellar and superior
cerebellar arteries
41. Blood Supply of Midbrain
• The major blood supply to the midbrain is
derived
mainly from branches of the Basilar Artery:
1. Posterior cerebral artery: forms a plexus
in the interpeduncular fossa, branches from this
plexus supply a wide area if the midbrain
2. Superior cerebellar artery: supplies
dorsal areas around the central gray and inferior
colliculus.
3. Posterior communicating artery
42. Blood Supply of
Cerebellum
1. Superior Cerebellar Artery-
Superior surface of the
cerebellum.
2. Anterior Inferior
Cerebellar Artery-
Anterior part of inferior
surface.
3. Posterior Inferior
Cerebellar Artery-
posterior part of inferior
surface.
4. The superior, middle and
inferior peduncles are
supplied by SCA, AICA &
PICA respectively.
43.
44. Veins of brain
• Thin walled
• No muscular tissue in their wall
• No valves
• Lie in the subarachnoid space
• Drain into cranial venous sinuses
• Two groups: External cerebral veins and
internal cerebral veins
45.
46. External Cerebral Veins
• Superior cerebral veins: pass upward over lateral
surface to empty into superior sagittal sinus
• Superficial middle cerebral vein: drains lateral
surface, runs lateral sulcus to empty into cavernous sinus
• Deep middle cerebral vein: drains insula.
Joined by anterior cerebral vein and striate veins to form
basal vein which joins great cerebral vein to drain into
straight sinus
47. Internal Cerebral Veins
• Two in number
• Formed by union of thalamostriate vein and
choroid vein
• Runs posteriorly and unite beneath splenium
of corpus callosum to form great cerebral vein
• Ultimately drains into straight sinus
48. Veins of the Spinal Cord
• The veins of the spinal cord drain into six
tortuous longitudinal channels that
communicate superiority within the skull with
veins of the brain and venous sinuses. They
drain mainly into the internal vertebral venous
plexus.
