Blood supply of the brain
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The document summarizes the blood supply of the brain. It begins by noting the brain's high metabolic demands and sensitivity to hypoxia. It then discusses the various arterial systems that supply the brain, including the internal carotid and vertebral arteries, as well as the arterial circle of Willis. It provides details on the territories supplied by the anterior, middle, and posterior cerebral arteries. It also briefly discusses the venous drainage of the brain and blood-brain barrier.
Blood supply of the brain
- 1. Blood supply of the Brain Dr. Suresh Managutti
- 2. Blood supply of brain
- 4. Blood supply of Brain
- 5. Blood supply of brain Introduction- Blood supply to brain- continuous , high metabloic demands for O2 and Glucose Brain- higly sensitive to hypoxia (inadequate O2) & hypoglycemia (subnormal blood glucose) Consciuosness is lost within 10 seconds of blood flow cessation Irreversible brain damage occurs at 4 minutes & completed in 10 minutes
- 6. Blood supply of brain Brain- metabolically most active - depends on aerobic metabolism Brain- 2% of body weight, receives 20% cardiac output - consumes 20% of total O2
- 7. Blood supply of brain • Cerebrovascular diseases – thrombosis, embolism, haemorrhage- 3rd most common cause of death • Neurological signs- depend on site of lesion • Adequate knowledge of blood supply of brain is essential in proper diagnosis & treatment. • Arterial occlusion by a thrombus – leads to infarction of portion of brain- supplied by affected artery- most common type of CV disease
- 8. Blood supply of brain Arterial supply - Vertebral artery system - Carotid artery system - Arterial circle of Willis - Course & branches of arteries - Arterial supply of cerebrum, cerebellum, brain stem, other parts - Clinical correlation
- 9. Blood supply of brain Venous drainage - Characteristic features - Cerebral veins- formation, course, tributaries and destiny - Venous drainage of different surfaces of cerebral hemispheres
- 10. Blood supply of brain Blood Brain Barrier-BBB - Structure - Areas of brain devoid of BBB Blood CSF Barrier - Structure of Blood – CSF Barrier Carotid & Vertebral angiogram
- 11. Vertebro-basilar & Internal carotid arterial system
- 12. Arteries of Brain - paired internal carotid & vertebral arteries - Extensive system of branches - Vertebral arteries – origin, course, branches and ending- basilar artery - Basilar Artery- beginning, course, parts, ending & branches - Internal carotid artery- origin, course, parts, ending & branches
- 13. Arterial circle of Willis • Major arteries supplying brain – branches of basilar artery & Internal carotid artery • Interconnected one another at base of brain • Six sided polygon of arteries- Circle of Willis • Formed – interpeduncular fossa • Lies in interpeduncular cistern • Most of supply to brain
- 14. Arterial circle of Willis Circle of Willis Formed by • Anteriorly- anterior cerebral & anterior communicating A • Posteriorly-basilar artery dividing in to 2 posterior cerebral arteries • Laterally – on each side by posterior communicating artery connecting ICA with posterior cerebral A
- 15. Functional significance of Circle of Willis • Little or no mixing of blood streams • A. of 2 vertebral arteries in the basilar artery • B. of 2 anterior cerebral arteries in the anterior communicating artery • C. of Internal carotid & posterior cerebral arteries Normally • Right ½ of brain supplied by- Rt vertebral & Rt ICA • Left ½ of brain supplied by- Lt vertebral & Lt ICA • If one of major arteries is blocked, it provides collateral circulation
- 16. Circle of Willis
- 17. Vertebro-Basilar system Vertebral artery- origin, course , parts & branches Branches of cranial part- 1. Anterior spinal artery (1) 2. Posterior spinal arteries (2) 3. Posterior inferior cerebellar artery (2) 4. Meningeal branches 5. Medullary branches
- 18. Vertebral artery
- 19. Basilar artery Formation, course, termination & branches Branches of basilar artery 1. Pontine branches 2. Anterior inferior cerebellar artery 3. Labyrinthine artery 4. Superior cerebellar artery 5. Posterior cerebral arteries
- 20. Posterior cerebral artery Beginning, course, and branches Branches of PCA 1. Anterior temporal branch 2. Posterior temporal branch 3. Parieto-occipital branch 4. Calcarine artery 5. Posterior choroidal artery
- 21. PCA
- 22. Carotid System
- 23. Internal carotid artery (ICA) Origin, course, parts, termination, branches Branches of cerebral (4th) part of ICA 1. Ophthalmic artery 2. Posterior communicating artery 3. Anterior choroidal artery 4. Anterior cerebral artery 5. Middle cerebral artery
- 24. ICA 4th Part branches
- 25. Anterior cerebral artery • Terminal branch of ICA • Course • Supply most of the medial surface of cerebrum • Branches - Orbital branches, central branches, frontopolar artery, pericallosal artery-parietal branches, callosomarginal artery- frontal branches
- 26. ACA -diagram
- 27. Middle cerebral artery • Larger terminal branch of ICA • 30% of carotid blood flow • Runs in stem of lateral sulcus, posterior ramus of lateral sulcus breaks up in to branches • Branches of MCA - orbitofrontal, pre-rolandic, rolandic artery, anterior parietal, posterior parietal, angular artery, anterior temporal & posterior temporal artery
- 28. MCA
- 29. Branches of the main arteries of brain Cerebral part of ICA 4th part of Vertebral artery Basilar artery Ophthalmic artery Meningeal branches Anterior inferior cerebellar artery Anterior cerebral artery Anterior spinal artery Labyrinthine artery Middle cerebral artery Posterior spinal artery Pontine branches Posterior communicating artery Posterior inferior cerebellar artery Superior cerebellar artery Anterior choroidal artery Medullary branches Posterior cerebral artery
- 30. Arterial supply of cerebrum • 3 pairs of cerebral arteries – anterior, middle & posterior • Branching pattern of cerebral arteries – cortical branches, central branches & choroidal branches
- 31. Cortical branches • Supply outer portion of cerebrum • Freely anastomose & form network in pia , on the surface of cerebral cortex • From this network branches pierce cortex at right angle • After entering cortex become end arteries • 2 types of end arteries - Short- confine only to cortex - Long- pass through cortex & reach outer portion of white matter
- 32. Central branches • Numerous, slender, thin walled perforating branches • Supply centrally located parts of cerebrum- corpus callosum, internal capsule etc. • End arteries • Arise in the region of circle of Willis • Are arranged in to 4 groups
- 33. Central branches
- 34. • Anteromedial group- ACA & ant commu. A, anterior perforated substance- supply ant limb of internal capsule(IC), corpus striatum & anterior part of hypothalamus • Anterolateral group(lateral striate arteries)- proximal part of MCA, pierce ant perforated substance – supply ant limb of IC, caudate & lentiform nuclei- largest lateral striate artery from MCA, susceptible to rupture- Charcot’s artery of cerebral haemorrhage
- 35. • Posteromedial group-proximal part of PCA & adjoining part of post. Commu. A, enter post. perforated substance, supply thalamus, subthalamus & hypothalamus • Posterolateral group-PCA, supply thalmus & geniculate bodies
- 36. Choroidal branches • Form network of capillaries, project into the ventricles • Invaginate the layers of pia mater and ependyma forming choroid plexus • Anterior choroidal artery- arises from ICA, runs posteriorly near optic tract, crosses uncus, enter choroid plexus in inferior horn of lateral ventricle • Posterior choroidal artery- arises from PCA, encircles around midbrain, to enter the choroid plexus of 3rd and lateral ventricles through transverse fissure
- 37. Arterial supply of different surfaces of cerebral hemisphere • Arterial supply of superolateral surface- MCA- primary motor & sensory areas, frontal eyefield, in the dominant hemisphere- Broca’s & Wernicke’s speech areas • Narrow strip 2.5 cm adjoining superomedial border up to parieto occipital sulcus- ACA
- 39. • Arterial supply of medial surface - Anterior 2/3rd of medial surface by ACA - Region includes- paracentral lobule, concerned with perineum, leg and foot - Temporal pole of temporal lobe-MCA - Occipital lobe is supplied by PCA
- 41. • Arterial supply of inferior surface -Most of inferior surface except temporal pole – PCA - Lateral part of orbital surface of frontal lobe & temporal pole of temporal lobe- MCA - Medial part of orbital surface of the frontal lobe –ACA
- 43. Arterial supply of different surfaces of cerebral hemisphere
- 44. Arterial supply of other parts of brain Corpus striatum & Internal capsule- mainly central branches of MCA, small part by central branches of ACA Thalamus- central branches of post commu.a. PCA, & basilar arteries Midbrain- PCA, Superior cerebellar, & Basilar A Pons- Basilar, superior cerebellar, & ant. Inf. Cerebellar arteries Cerebellum- superior, anterior inferior & posterior inferior cerebellar arteries
- 45. Coronal section of cerebral hemisphere- deep structures arterial supply
- 46. Venous drainage of brain • Veins of the brain drain into intracranial dural venous sinuses • Intracranial dural venous sinuses open into Internal jugular vein • Veins emerge from brain, traverse subarachnoid space • Pierce the arachnoid mater to drain into dural venous sinuses
- 47. Characteristic features of venous drainage of brain • Venous return does not follow arterial pattern • Extremely thin walled , absence of smooth muscles in their walls • No valves • Run mainly in the subarachnoid space • Enter obliquely into dural venous sinuses against flow of blood to prevent collapse following increased intracranial pressure as they are thin walled • Veins of brain- cerebral veins, cerebellar veins, veins of the brain stem
- 48. Cerebral veins • Cerebral veins- external (superficial)cerebral veins, internal (deep)cerebral veins • External (superficial) cerebral veins - External cerebral veins drain the surface(cortex) of cerebral hemisphere & are 3 groups a) Superior cerebral veins b) Middle cerebral veins c) Inferior cerebral veins
- 49. Superior cerebral veins • 8-12 in number • Upper part of superolateral surface and medial surfaces of cerebral hemisphere • Ascend upwards, pierce arachnoid mater , traverse subdural space to enter superior sagittal sinus • Anterior veins open at right angle • Posterior veins open obliquely against flow of blood • Embryologically it is due to backward growth of rapidly increasing cerebrum • It prevents their collapse by increased CSF pressure
- 51. Middle cerebral veins 4 in number 2 on each side A) Superficial middle cerebral vein B) Deep middle cerebral vein Superficial middle cerebral vein – - Lies superficially in lateral sulcus - Anteriorly it runs forwards to drain into cavernous sinus - Posteriorly it communicates with superior sagittal sinus via superior anastomotic vein of Trolard - Communicates with transverse sinus via inferior anastomotic vein of Labbe
- 53. • Deep middle cerebral vein - Lies deep in the lateral sulcus on the insula along with MCA - Runs downwards & forwards & joins the anterior cerebral vein to form the basal vein • Inferior cerebral veins - Many in number, smaller in size - Drain inferior surface & lower parts of medial & superolateral surfaces - Drain into near by dural venous sinuses , viz. transverse sinus
- 54. Other veins • Anterior cerebral vein - Accompanies ACA around corpus callosum - Drains parts of medial surface which cannot be drained into sup or inf sagittal sinuses • Basal vein of Rosenthal - Formed at base of brain in the region of ant perforated substance - It is formed by union of 3 veins- anterior cerebral, deep middle cerebral & striate veins.
- 56. • Striate veins emerge from the ant perforated substance • Basal vein runs posteriorly around midbrain • Medial to uncus & parahippocampus • Terminate into the great cerebral vein of Galen below the splenium of corpus callosum • Tributaries - Besides 3 formative tributaries, basal vein receives the tributaries from - cerebral peduncle - Uncus & parahippocampus - structures of interpeduncular fossa - optic tract & olfactory trigone - inferior horn of lateral ventricle
- 57. Internal cerebral veins • 2 internal cerebral veins • 1 on either side of midline in the tela choroidea of 3rd ventricle • Formed at foramen of Monro by union of 3 veins • Thalamostriate, septal & choroidal • 2 internal cerebral veins run on either side of midline between 2 layers of tela choroidea of 3rd ventricle • Unite beneath the splenium of corpus callosum to form great cerebral vein of Galen which empties into straight sinus
- 59. • The thalamostriate, septal & choroidal veins are most important deep veins of cerebrum. • Thalamostriate vein drains thalamus & basal ganglia • Septal vein drains septum pellucidum • Choroidal vein drains choroid plexus
- 60. Great cerebral vein of Galen Single vein, 2cm in length • Formed by union of 2 internal cerebral veins below & behind splenium of corpus callosum • Immediately receives 2 basal veins and after short backward course joins the inferior sagittal sinus to form straight sinus • Tributaries- - Internal cerebral veins - Basal veins - Veins from colliculi - Veins from cerebellum - -adjoining part of occipital lobes of cerebrum
- 62. Great cerebral vein of Galen
- 63. Blood brain barrier -BBB • Capillary endothelial cells • Basement membrane • Foot processes of astrocytes • Barrier protects brain from potentially harmful substances • Allows gases and nutrients to enter the tissue
- 64. BBB
- 65. Areas of brain devoid of BBB • Pineal gland • Posterior lobe of pituitary • Tuber cinereum • Wall of supraoptic recess of 3rd ventricle • Area postrema of floor of 4th ventricle
- 66. Blood CSF barrier • Endothelial cells of capillaries • Basement membrane of endothelium • Basement membrane of choroidal epithelial cells • Scattered pale cells between 2 basement membranes • Free passage of water, gases & lipid soluble substances • Prevents macromolecules entry-proteins & hexoses except glucose
- 67. Clinical anatomy • Congenital cerebral aneurysms-berry shape • Subarachnoid haemorrhage – arterial rupture • Subdural haemorrhage- venous • Extradural haemorrhage- meningeal arteries • Intracerebral haemorrhage- charcots artery-MCA • Carotid siphon • Cerebral thrombosis/embolism • Occlusion of cerebral arteries • Cerebral angiography • Cerebro vascular accdidents-thrombosis, embolism, haemorrhage
- 68. CT Scan of Brain- extradural haemorrhage
- 69. CT Scan of Brain- subradural haemorrhage
- 70. CT Scan of Brain- subarachnoid haemorrhage
- 71. CT Scan of Brain- intracerebral haemorrhage