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7/27/2019 Lec 14 Blood Supply
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Blood SupplyBrain
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Introduction One of the most metabolically active systems
Normal cerebral blood flow is about 50 mL/100 g of brain tissue/min
◦ Thus, a brain of average weight (1400 - 1500 g) has a
normal blood flow of 700 - 750 mL/min
A blood flow of 25 mL/100 g of brain tissue/min
constitutes ischemic penumbra (a dangerously
deficient blood supply leading to loss of brain cells)
A blood flow of 8 mL/100 g of brain tissue/min leadsto an almost complete loss of functional neurons
Consciousness is lost within 10 seconds of the
cessation of blood supply to the brain
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Arterial Supply of the Brain
Derived from two arteries: (1) the
internal carotid artery and (2) the
vertebral artery
These arteries and their branches arise inpairs that supply blood to both sides of
the brain
Basilar artery◦ Is a single artery
◦ But its braches are always in pairs
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Internal Carotid Artery - Branches
Ophthalmic artery
Posterior communicating artery
◦ Also supplies blood to the hypophysis, infundibulum,
parts of the hypothalamus, thalamus, and hippocampus Choroidal artery
◦ Choroidal plexus of lateral ventircle
◦ Also supplies crus cerebri, lateral geniculate body,
optic tract, & internal capsule Anterior cerebral artery
Middle cerebral artery
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Vertebro-Basilar Circulation
System includes the two vertebral arteries,the basilar artery (which is formed by the
union of the two vertebral arteries), and
their branches
Supplies the medulla, pons, mesencephalon,
and cerebellum
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Vertebral artery - Branches
Meningeal branches◦ Bone & dura in posterior cranial fossa
Posterior spinal artery
Anterior spinal artery◦ Contributing branches from each vertebral A.
Posterior inferior cerebellar artery◦
Choroidal plexus of 4
th
ventricle, vermis, centralnucleus, & undersuface of cerebellum, & medullaoblongata
Medullary arteries
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Anterior Spinal Artery
Formed by union of two small arisingfrom each vertebral artery
Supplies the medial structures of the
medulla, which include the pyramids,medial lemniscus, medial longitudinal
fasciculus, hypoglossal nucleus, and the
inferior olivary nucleus Also Anterior 2/3rd of Spinal cord
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Posterior Inferior Cerebellar
Artery (PICA) Supplies the regions of the lateral medulla that include the
spinothalamic tract, dorsal and ventral spinocerebellar
tracts, descending sympathetic tract, descending tract of
cranial nerve V, and nucleus ambiguus
Also supplies the vermal region and inferior-lateral surfaceof the cerebellar hemisphere
Wallenberg's syndrome
◦ Damage to the lateral medulla esp. N. ambiguss
◦ Presents as lack of coordination in speech
(dysphonia), disturbance in articulation (dysarthria),and dysphagia (difficulty in swallowing)
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Posterior Spinal Artery (PSA)
Majority of cases it arises from PICA
Supplies the fasciculus gracilis and
cuneatus as well as the gracile and
cuneate nuclei, spinal trigeminal nucleus,dorsal and caudal portions of the inferior
cerebellar peduncle, and portions of the
solitary tract and dorsal motor nucleus of the vagus nerve
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Basilar artery - Branches
Pontine arteries
Labyrinthine artery
Anterior inferior cerebellar artery
Superior cerebellar artery
Posterior cerebral arteries
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Pontine Arteries
Several pairs of pontine arteries arise from thebasilar artery
Paramedian arteries
◦ Supply the medial portion of the lower and upperpons
Include pontine nuclei, corticopontine fibers, the corticospinal
and corticobulbar tracts, and portions of the ventral pontine
tegmentum, and medial lemniscus
Short circumferential arteries◦ Supply substantia nigra and lateral portions of the
midbrain tegmentum
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Labyrinthine (Internal
Auditory) Artery
Supplies the cochlea and labyrinth
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Anterior Inferior Cerebellar
Artery (AICA)
Supplies the ventral and inferior surface
of the cerebellum and lateral parts of the
pons
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Superior Cerebellar Artery
Supplies the rostral level of the pons,caudal part of the midbrain, and superior
surface of the cerebellum
◦ Includes portions of the superior and middlecerebellar peduncles, the medial and laterallemniscus, part of the spinal trigeminal nucleus
and tract, the spinothalamic tract, and
superior cerebellar peduncle
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25Circulation at the base of the brain
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Major Cerebral Blood Vessels
1. Anterior cerebral artery
2. Middle cerebral artery
3. Posterior cerebral artery
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Anterior cerebral artery
Anterior communicating artery
◦ Also supplies anterior hypothalamus, including preoptic and
suprachiasmatic areas
Cortical branches
◦ Oribtal branches – Orbital & Medial surface of Frontal lobe
◦ Frontopolar branches - Medial portions of the frontal lobe and lateralparts of the convexity of the hemisphere
◦ Callosomarginal artery - Paracentral lobule and portions of thecingulate gyrus
◦ Pericallosal artery - Precuneus
Central branches
◦ Medial striate artery (Recurrent artery of Heubner)
Supplies anteromedial part of the head of the caudate nucleus and
parts of the internal capsule, putamen, and septal nuclei
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Middle Cerebral Artery
Cortical branches
Central branches
◦ Lenticulostriate arteries
◦ Lateral striate branches
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Middle Cerebral Artery – Branches
The lenticulostriate branches◦ Supply the putamen, caudate nucleus, and anterior
limb of the internal capsule
Orbitofrontal artery
◦ Parts of the frontal lobe
Precentral (pre-Rolandic) and central (Rolandic)
branches
◦ Supply different regions of the frontal lobe
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Middle Cerebral Artery – Branches
Anterior and posterior parietal arteries◦ Supply different regions of the parietal lobe
Angular branch
◦ Supplies angular gyrus
Anterior, middle, and posterior temporal
arteries
◦ Different regions of temporal lobe◦ Branches of the posterior temporal artery
also supply the lateral portions of the occipitallobe
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Posterior Cerebral Artery
Cortical branches Central branches
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Posterior Cerebral Arteries
Supply most of the midbrain, thalamus,and subthalamic nucleus
Anterior and posterior temporal andparieto-occipital branches
◦ Supply the temporal lobes and medial and
inferior occipital lobes of the cerebral cortex Calcarine artery
◦ Supplies the primary visual cortex
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Arteries of Specific brain areas
Corpus striatum & Internal capsule Thalamus
Midbrain
Pons
Medulla Oblongata
Cerebellum
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V i f B i
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Veins of Brain External Cerebral Veins
◦ Superior cerebral veins◦ Superficial middle cerebral veins
◦ Deep middle cerebral veins
◦ Inferior cerebral veins
◦ Anterior cerebral veins
◦ Striate veins
◦ Basal vein
Internal Cerebral Veins
◦ Thalamostriate veins
◦ Choroid veins
◦ Great Cerebral vein 55