4. There are four cerebral arteries. The largest are the two internal carotid arteries, the left
and right branches of the common carotid arteries in the neck which enter the skull, as
opposed to the external carotid branches which supply the facial tissues. The two
smaller arteries are the vertebral arteries, which branch from the subclavian arteries
which primarily supply the shoulders, lateral chest and arms.
Within the cranium, which houses the brain, the two vertebral arteries fuse into the
basilar artery, which is located underneath, and primarily supplies, the brainstem.
Both internal carotid arteries, within and along the floor of the cerebral vault, are
interconnected via the anterior communicating artery. Additionally, both internal carotid
arteries are interconnected with the basilar artery via bilateral posterior communicating
arteries.
The Circle of Willis, long considered to be an important anatomic vascular formation,
provides backup circulation to the brain. In case one of the supply arteries is occluded,
the Circle of Willis provides interconnections between the internal carotid arteries and
basilar artery along the floor of the cerebral vault, providing blood to tissues that would
otherwise become ischemic.
6. Each artery give rise to two set of branches
Cortical branches
Ramify on the surface of the
Cerebral hemisphere and
Supply the cortex.
Central or perforating branches
Pass deep into the substance of
the cerebral hemisphere to
supply the structure within it.
Consist of six main groups.
7. Circle of Willis
Named after Thomas Willis
An important anastomosis of arteries around the
sella turcica.
Equalizes blood pressure in the brain and can
provide collateral channels should one vessel
become blocked
Connects:
Anterior-Anterior: Anterior communicating artery.
Anterior-Posterior: Posterior communicating artery.
8. Circle Of Willis
M1 segment- lentriculostriate arteries supply basal
ganglia and most of internal capsule
Superior MCA branch- supplies lateral and inferior
frontal lobe and anterior parts of parietal lobe
Inferior MCA branch-supplies lateral temporal lobe,
posterior parietal and lateral occipital lobe
9. Formation of Circle of Willis
Circle of Willis
Anterior Cerebral
Artery (ACA)
Anterior
Communicating Artery
(ACoA)
Middle Cerebral Artery
(MCA)
Posterior
Communicating Artery
(PCoA)
Posterior Cerebral
Artery (PCA)
Anterior
Circulation
Posterior
Circulation
12. Anterior Cerebral Artery
Arises from internal carotid
Supplies anterior portion of
basal ganglia, corpus
callosum, medial & superior
portions of frontal lobe and
anterior parietal lobe
Key Functional Areas:
Primary motor cortex for leg
and foot areas, urinary
bladder
Motor planning in medial
frontal lobe
Middle and anterior corpus
callosum- communication
between hemispheres
Anterior Cerebral Artery
15. Middle Cerebral Artery
Arises from the internal carotid
Passes laterally under frontal lobe and between
the temporal and frontal lobes
Supply basal ganglia and most of internal
capsule
Superior MCA branch- supplies lateral and
inferior frontal lobe and anterior parts of
parietal lobe
Inferior MCA branch-supplies lateral temporal
lobe, posterior parietal and lateral occipital
lobe
16. Middle Cerebral Artery
Key Functional Areas
Primary motor cortex for face, arm and leg
Primary somatosensory cortex for face, arm, leg
Brocas language area (Superior MCA)
Wernickes language area (Inferior MCA)
23. VENOUS DRAINAGE
Do not follow the arterial pattern
Thin walled and devoid of valve.
Drain into dural venous sinus against the flow of blood
The veins are arranged in three sets.
They consist of :
1. Cerebral veins consists of superficial/ external group
and deep/ internal group.
2. Cerebellar veins
3. Veins of brainstem
24. Cerebral Veins
Drain the cortex
and subcortical
white matter.
Drain the substance
of the brain including
basal ganglia,and
diencephalon.
Both superficial and deep veins communicate by
anastomotic veins.
Superficial veins: Deep veins:
25. Cerebral Veins
Superficial veins
1. Superior cerebral veins (8-12 in no.)
2. Superficial middle cerebral vein
3. Inferior cerebral veins
Deep veins
1. Internal cerebral veins ( right and left)
2. The paired basal veins (of ROSENTHAL)
3.The great cerebral vein of GALEN
26. Superficial cerebral veins (lateral view)
Superior cerebral veins
Superficial middle
cerebral vein
Superior cerebral veins
32. Blood-brain barrier
The barrier that
protects the brain
and spinal cord
from harmful
substance ( toxic
drugs and other
exogenous material)
while allowing gas
and nutrients to
enter the CNS.
33. Physiological consideration of
cerebral circulation
Ever active brain with little metabolic reserve
Brain 2% of body wt receive 1/5th of cardiac
output and 20% of oxygen
Blood flow 750 ml /min
Circulation time from ICA to internal jugular
vein 7 seconds
37. Symptoms
Sudden headaches (most severe
headache ever!)
• Stiff neck, vomiting, nausea,
vision or
speech impairment, weakness in any
part of the body, seizure, increased
sensitivity to light, and loss of
consciousness
• Sudden death
38. Medial medullary syndrome
(occlusion of vertebral artery or of branch of
vertebral or lower basilar artery)
Signs and symptoms:Structures involved
On side of lesion
Paralysis with atrophy of half the tongue: Ipsilateral twelfth
nerve
On side opposite lesion
Paralysis of arm and leg, sparing face; impaired tactile and
proprioceptive sense over half the body: Contralateral
pyramidal tract and medial lemniscus
39. Lateral medullary syndrome
(occlusion of any of five vessels may be responsible—
vertebral, posterior inferior cerebellar)
On side of lesion
Pain, numbness, impaired sensation over half the face:
Descending tract and nucleus fifth nerve
Ataxia of limbs, falling to side of lesion: Uncertain—
restiform body, cerebellar hemisphere, cerebellar fibers,
spinocerebellar tract (?)
Nystagmus, diplopia, oscillopsia, vertigo, nausea, vomiting:
Vestibular nucleus
40. Lateral medullary syndrome
Horner's syndrome (miosis, ptosis, decreased sweating):
Descending sympathetic tract
Dysphagia, hoarseness, paralysis of palate, paralysis of vocal
cord, diminished gag reflex: Issuing fibers ninth and tenth
nerves
Loss of taste: Nucleus and tractus solitarius
Numbness of ipsilateral arm, trunk, or leg: Cuneate and
gracile nuclei
Weakness of lower face: Genuflected upper motor neuron
fibers to ipsilateral facial nucleus
On side opposite lesion
Impaired pain and thermal sense over half the body,
sometimes face: Spinothalamic tract
42. Strokes affecting the posterior circulation or
vertebrobasilar system, present with symptoms such as
diplopia, vertigo, coma at onset, crossed sensory loss,
bilateral motor signs, isolated field deficits, pure motor
and sensory deficits, dysarthria and dysphagia.
While each patient presentation is unique, depending on
the blood vessel that is affected and the area of brain
infarcted, these are a list of general symptoms in relation
to anterior and posterior circulation.
43. Middle Cerebral Artery(Applied)
- Most common stroke syndrome.
- contralateral weakness
l face, arm, and hand more than legs
- contralateral sensory loss
l face, arm, and hand more than legs
l visual field cut
damage to optic radiations
44. Middle Cerebral Artery (Contd.)
Aphasia: language disturbances
more likely with L. Hemi. damage
Broca's: production
Wernicke's: comprehension ~
