blood supply of the brain and spinal cord

Blood Supply of Blood Supply of the Brain & the Brain & Spinal CordSpinal Cord

Reynaldo V. Lopez, M.D. Senior Lecturer

Department of Anatomy

Objectives: Objectives:

Describe Describe the main arteries and veins the main arteries and veins supplying the brain and spinal cord.supplying the brain and spinal cord.

Discuss Discuss the areas of the cerebral cortex the areas of the cerebral cortex and spinal cord supplied by a particular and spinal cord supplied by a particular artery and understand the dysfunction artery and understand the dysfunction that may arise if the artery is blocked.that may arise if the artery is blocked.

Describe Describe in detail the circle of Willis and in detail the circle of Willis and the blood supply to the internal capsule. the blood supply to the internal capsule.

Blood Supply to Blood Supply to the Brainthe Brain

Arteries of the Brain Arteries of the Brain

1. Internal carotids 1. Internal carotids (2) - anterior (2) - anterior circulationcirculation

2. Vertebral arteries 2. Vertebral arteries (2) - posterior (2) - posterior circulationcirculation

- branches - branches anastomose on the anastomose on the inferior surface of inferior surface of the brain to form the the brain to form the circle of Williscircle of Willis

Circle of Willis Circle of Willis

INTERNAL CAROTID INTERNAL CAROTID ARTERYARTERY

Anterior CirculationAnterior Circulation

Internal Carotid Artery Internal Carotid Artery begins at the begins at the

bifurcation of the bifurcation of the common carotid common carotid artery where it artery where it possesses a localized possesses a localized dilatation called the dilatation called the carotid sinuscarotid sinus

ascends the neck & ascends the neck & perforates the base of perforates the base of the skull by passing the skull by passing through the through the carotid carotid canal of the temporal canal of the temporal bonebone

Internal Carotid Artery Internal Carotid Artery

runs horizontally forward thru the runs horizontally forward thru the cavernous sinuscavernous sinus

emerges on the anterior clinoid process by emerges on the anterior clinoid process by perforating the dura materperforating the dura mater

Internal Carotid Artery Internal Carotid Artery

enters the enters the subarachnoid space subarachnoid space by piercing the by piercing the arachnoid mater & arachnoid mater & turns posteriorly to turns posteriorly to the region of the the region of the medial end of the medial end of the lateral cerebral lateral cerebral sulcussulcus

here it divides into here it divides into the the anterior & middle anterior & middle cerebral arteriescerebral arteries

Branches of the Cerebral Branches of the Cerebral Portion Portion

1. 1. Ophthalmic arteryOphthalmic artery – arises as the internal – arises as the internal carotid artery emerges from the carotid carotid artery emerges from the carotid sinussinus

- enters the orbit thru the optic canal - enters the orbit thru the optic canal below & lateral to the optic nervebelow & lateral to the optic nerve

- supplies the - supplies the eye & other orbital eye & other orbital structuresstructures

- its terminal branches supply the - its terminal branches supply the frontal frontal area of the scalp, area of the scalp, thethe ethmoid & frontal ethmoid & frontal sinuses sinuses & the& the dorsum of the nose dorsum of the nose

Branches of the Cerebral Branches of the Cerebral PortionPortion

2. 2. Posterior communicating artery Posterior communicating artery – runs – runs posteriorly above the oculomotor nerve to posteriorly above the oculomotor nerve to join the join the posterior cerebral arteryposterior cerebral artery, thus , thus forming part of the circle of Willisforming part of the circle of Willis


3.3. Choroidal artery Choroidal artery – – passes posteriorly passes posteriorly close to the optic close to the optic tract, enters the tract, enters the inferior horn of inferior horn of the lateral the lateral ventricle & ends ventricle & ends in the choroid in the choroid plexusplexus


4.4. Anterior cerebral artery Anterior cerebral artery – curves backward – curves backward over the corpus callosum & anastomoses over the corpus callosum & anastomoses with the posterior cerebral artery; with the posterior cerebral artery;

- cortical branches supplies - cortical branches supplies all the medial all the medial surface of the cerebral cortexsurface of the cerebral cortex as far back as as far back as the parieto-occipital sulcus;the parieto-occipital sulcus;

- supplies a strip of cortex about 1 inch wide - supplies a strip of cortex about 1 inch wide on the adjoining lateral surface thus on the adjoining lateral surface thus supplying the “leg area“ of the precentral supplying the “leg area“ of the precentral gyrusgyrus


Anterior cerebral artery Anterior cerebral artery


5.5. Middle cerebral artery Middle cerebral artery – largest branch of – largest branch of the internal carotid, runs laterally in the the internal carotid, runs laterally in the lateral cerebral sulcuslateral cerebral sulcus


5.5. Middle cerebral artery Middle cerebral artery – cortical branches – cortical branches supply the supply the entire lateral surface of the entire lateral surface of the hemispherehemisphere, except for the narrow strip , except for the narrow strip supplied by the anterior cerebral arterysupplied by the anterior cerebral artery

- supplies - supplies all the motor area all the motor area except the except the “leg area”“leg area”

- central branches supply the lentiform & - central branches supply the lentiform & caudate nuclei & the internal capsulecaudate nuclei & the internal capsule

VERTEBRAL ARTERYVERTEBRAL ARTERYPosterior CirculationPosterior Circulation

Vertebral Artery Vertebral Artery

branch of the 1branch of the 1stst part part of the subclavian of the subclavian arteryartery

ascends the neck thru ascends the neck thru the foramina in the the foramina in the transverse processes transverse processes of the upper 6 cervical of the upper 6 cervical vertebraevertebrae

Vertebral Artery Vertebral Artery

enters the skull through the enters the skull through the foramen magnumforamen magnum at the lower border of the pons, joins the vessel at the lower border of the pons, joins the vessel

of the opposite side to form the of the opposite side to form the basilar arterybasilar artery

Branches of the Cranial Branches of the Cranial PortionPortion

1.1. Meningeal branches Meningeal branches – are small & supply the bone & dura in the posterior – are small & supply the bone & dura in the posterior cranial fossacranial fossa

2.2. Posterior spinal artery Posterior spinal artery – may arise from the vertebral artery or the posterior – may arise from the vertebral artery or the posterior inferior cerebellar artery;supplies the posterior 1/3 of the spinal cordinferior cerebellar artery;supplies the posterior 1/3 of the spinal cord

3. 3. Anterior spinal artery Anterior spinal artery – formed from a contributory branch from each – formed from a contributory branch from each vertebral artery; vertebral artery;

descends as a single artery on the anterior surface of the medulla descends as a single artery on the anterior surface of the medulla oblongata & spinal cordoblongata & spinal cord


4.4. Posterior inferior Posterior inferior cerebellar artery cerebellar artery – – largest branch; largest branch; supplies the:supplies the:

a)a) inferior surface of the inferior surface of the vermis, vermis,

b)b) central nuclei of the central nuclei of the cerebellumcerebellum

c)c) undersurface of the undersurface of the cerebellar cerebellar hemisphere hemisphere

d)d) medulla oblongata medulla oblongata

e)e) choroid plexus of the choroid plexus of the 44thth ventricle ventricle


5.5. Medullary arteries Medullary arteries – very small branches to – very small branches to the medulla oblongata the medulla oblongata

BASILAR ARTERYBASILAR ARTERYPosterior CirculationPosterior Circulation

Basilar Artery Basilar Artery formed by the union of 2 vertebral arteriesformed by the union of 2 vertebral arteries ascends in a groove on the anterior surface of ascends in a groove on the anterior surface of

the ponsthe pons at the upper part of the pons, divides into the at the upper part of the pons, divides into the

2 2 posterior cerebral arteriesposterior cerebral arteries

Branches Branches 1.1. Pontine arteries Pontine arteries – are small numerous – are small numerous

vessels that enter the substance of vessels that enter the substance of the ponsthe pons

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Branches Branches 2.2. Labyrinthine artery Labyrinthine artery – long narrow artery that – long narrow artery that

accompanies the facial & vestibulocochlear accompanies the facial & vestibulocochlear nerves into the internal acoustic meatus & nerves into the internal acoustic meatus & supplies the internal earsupplies the internal ear

2

Branches Branches 3. 3. Anterior inferior cerebellar artery Anterior inferior cerebellar artery – passes – passes

posteriorly & laterally and supplies the posteriorly & laterally and supplies the anterior and inferior parts of the cerebellumanterior and inferior parts of the cerebellum

3

Branches Branches 4.4. Superior cerebellar artery Superior cerebellar artery – arise close to the – arise close to the

termination of the basilar artery; supplies the termination of the basilar artery; supplies the superior surface of the cerebellumsuperior surface of the cerebellum

4

Branches Branches 5.5. Posterior cerebral artery Posterior cerebral artery – curves laterally & – curves laterally &

backward around the midbrain & is joined by the backward around the midbrain & is joined by the posterior communicating branch of the internal posterior communicating branch of the internal carotid arterycarotid artery

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Branches Branches

5.5. Posterior cerebral artery Posterior cerebral artery

- cortical branches supplies the:- cortical branches supplies the:a)a) inferolateral & medial surfaces of the temporal inferolateral & medial surfaces of the temporal

lobe lobe

b)b) lateral & medial surfaces of the occipital lobe lateral & medial surfaces of the occipital lobe (visual cortex)(visual cortex)

-- central branches supply:central branches supply:a)a) parts of the thalamus & lentiform nucleusparts of the thalamus & lentiform nucleus

b)b) midbrainmidbrain

c)c) pineal pineal

d)d) medial geniculate bodiesmedial geniculate bodies

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Arteries of the Brain (Inferior Arteries of the Brain (Inferior View) View)

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Arteries of the Brain (Frontal Arteries of the Brain (Frontal View) View)

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Arteries of the Brain (Medial Arteries of the Brain (Medial View) View)

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Arteries of the Brain (Lateral Arteries of the Brain (Lateral View) View)

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CLINICAL APPLICATIONCLINICAL APPLICATION

Congenital AneurysmsCongenital Aneurysms

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Intracerebral HemorrhageIntracerebral Hemorrhage

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ThrombosisThrombosis

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VEINS OF THE VEINS OF THE BRAINBRAIN

Veins Veins

have no muscular have no muscular tissue in their very thin tissue in their very thin wallswalls

possess no valvespossess no valves emerge from the brain emerge from the brain

& lie in the & lie in the subarachnoid spacesubarachnoid space

pierce the arachnoid pierce the arachnoid mater & meningeal mater & meningeal layer of the dura & layer of the dura & drain into the cranial drain into the cranial venous sinusesvenous sinuses

External Cerebral Veins External Cerebral Veins

1.1. Superior cerebral veins Superior cerebral veins – pass upward over the lateral surface of the cerebral – pass upward over the lateral surface of the cerebral hemisphere & empty into the hemisphere & empty into the superior sagittal sinussuperior sagittal sinus

2.2. Superficial middle cerebral veinSuperficial middle cerebral vein – drains the lateral surface of the cerebral – drains the lateral surface of the cerebral hemisphere & empties into the hemisphere & empties into the cavernous sinuscavernous sinus

3.3. Deep middle cerebral vein Deep middle cerebral vein – drains the insula & is joined by the – drains the insula & is joined by the anterior cerebral anterior cerebral && striate veins striate veins to form the to form the basal veinbasal vein

External Cerebral Veins External Cerebral Veins

Internal Cerebral Veins Internal Cerebral Veins

2 internal cerebral veins 2 internal cerebral veins – formed by the union of the – formed by the union of the thalamostriate vein thalamostriate vein & the & the choroid veinchoroid vein

- both run posteriorly in the tela choroidea of the 3- both run posteriorly in the tela choroidea of the 3rdrd ventricle ventricle & unite beneath the corpus callosum to form the & unite beneath the corpus callosum to form the great great cerebral veincerebral vein

-- great cerebral vein then empties into the great cerebral vein then empties into the straight sinusstraight sinus

Internal Cerebral Veins Internal Cerebral Veins

BLOOD SUPPLY OF THE BLOOD SUPPLY OF THE SPINAL CORDSPINAL CORD

ArteriesArteries1. 1. Posterior spinal arteries Posterior spinal arteries – may arise from the – may arise from the

vertebral artery or the posterior inferior vertebral artery or the posterior inferior cerebellar artery cerebellar artery

- descends on the anterior surface of the spinal - descends on the anterior surface of the spinal cord close to the posterior nerve rootscord close to the posterior nerve roots

- supplies the posterior 1/3 of the spinal cord- supplies the posterior 1/3 of the spinal cord

2. 2. Anterior spinal artery Anterior spinal artery – formed from a – formed from a contributory branch from each vertebral artery contributory branch from each vertebral artery

- descends as a single artery on the anterior - descends as a single artery on the anterior surface of the medulla oblongata & spinal cordsurface of the medulla oblongata & spinal cord

- supplies the anterior 2/3 of the spinal cord- supplies the anterior 2/3 of the spinal cord

Blood Supply of the Spinal Blood Supply of the Spinal CordCord

ArteriesArteries3. 3. Segmental spinal arteries Segmental spinal arteries – branches of – branches of

arteries outside the vertebral columnarteries outside the vertebral column

- these are the - these are the deep cervicaldeep cervical, , intercostalintercostal & & lumbar arterieslumbar arteries

ArteriesArteries4.4. Feeder arteries Feeder arteries – enter the vertebral – enter the vertebral

canal & anastomose with the anterior canal & anastomose with the anterior & posterior spinal arteries& posterior spinal arteries

Great anterior medullary artery of Great anterior medullary artery of AdamkiewiczAdamkiewicz

- may be the major source of blood to - may be the major source of blood to the lower 2/3 of the spinal cordthe lower 2/3 of the spinal cord

Blood Supply of the Spinal Blood Supply of the Spinal CordCord

VeinsVeins – – drain into 6 tortuous longitudinal channels drain into 6 tortuous longitudinal channels that communicate superiorly within the skull that communicate superiorly within the skull with the veins of the brain & the venous sinuseswith the veins of the brain & the venous sinuses

- drain mainly into the internal vertebral venous - drain mainly into the internal vertebral venous plexusplexus

Thank you Thank you for your for your

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blood supply of the brain and spinal cord

Documents

circle of artery

basilar artery branches

narrow artery

single artery

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labyrinthine artery

ophthalmic artery

subclavian artery