2. INTRODUCTION
• The brain is one of the most metabolically active organs of
the body as it depends on aerobic metabolism of glucose.
• Although the brain constitutes only 2% (1/50) of the total
body weight, it receives 20% (1/5) of the total cardiac
output and consumes 20% of the total O2 used by the
body.
• Cerebrovascular diseases (thrombosis, embolism, and
hemorrhage) are the third most common cause of death
and neurological signs depend on the site of lesion.
• Therefore, an adequate knowledge of the blood supply of
the brain is essential for proper diagnosis and treatment of
these diseases.
3. ARTERIES OF THE BRAIN
• The blood supply to the brain is provided by four arteries: two
vertebral arteries and two internal carotid arteries.
• The two vertebral arteries enter the skull through the foramen
magnum and unite at the lower border of the pons to form the
basilar artery, which ascends in the midline on the ventral surface
of the pons and at its upper border terminates by dividing into right
and left posterior cerebral arteries.
• Each internal carotid artery enters the cranial cavity through carotid
canal and the superior part of the foramen lacerum. It then takes a
sinuous course through the cavernous sinus, pierces the dural roof
of the sinus, and ends immediately lateral to the optic chiasma in
the region of anterior perforated substance by dividing into a larger
middle cerebral artery and a smaller anterior cerebral artery.
4.
5. CIRCLE OF WILLIS
• The branches of basilar and internal carotid
arteries anastomose at the base of brain
around the interpeduncular fossa forming a
six-sided polygon of arteries called circulus
arteriosus or circle of Willis.
• The circle of Willis lies in the interpeduncular
subarachnoid cistern and contributes most of
the arterial blood supply to the brain.
6. FORMATION OF CIRCLE OF WILLIS
• Anteriorly, by the anterior communicating and
the anterior cerebral arteries.
• Posteriorly, by the basilar artery dividing into
two posterior cerebral arteries.
• Laterally on each side, by the posterior
communicating artery connecting the internal
carotid artery with the posterior cerebral
artery
7.
8.
9. ARTERIAL SUPPLY OF THE CEREBRUM
• The cerebrum is supplied by three pairs of
cerebral arteries, viz. anterior, middle, and
posterior.
• Branching Pattern of Cerebral Arteries- The
cerebral arteries give three types of branches-
1. Cortical branches
2. Central branches
3. Choroidal branche
10.
11. ARTERIAL SUPPLY OF THE INTERNAL
CAPSULE
• The different parts of the internal capsule are
supplied by the following arteries:
1. Anterior limb: by medial striate branches of
the anterior cerebral artery and lateral striate
branches of the middle cerebral artery.
2. Genu: by recurrent artery of the Heubner
or direct branches from internal carotid artery.
3. Posterior limb: by lateral striate branches of
the middle cerebral artery and branches of the
anterior choroidal artery
