Cerebral Blood Flow PDF

# Cerebral Blood Flow ## Wayne State University Jared Kurdunowicz PT, DPT, NCS ## Outline - Blood - Arteries - Blood Brain Barrier - Regulation of Blood Flow - Veins and Cerebrospinal fluid - Sinuses and Cerebral Veins - Meninges, Folds, and Spaces - CSF and Ventricles - P...

# Cerebral Blood Flow ## Wayne State University Jared Kurdunowicz PT, DPT, NCS ## Outline - Blood - Arteries - Blood Brain Barrier - Regulation of Blood Flow - Veins and Cerebrospinal fluid - Sinuses and Cerebral Veins - Meninges, Folds, and Spaces - CSF and Ventricles - Pathology - Hemorrhage and Ischemia - Stroke Characteristics - Regions and syndromes - Other Pathologies # Arteries & Veins Outside the Skull - Common Carotid A. -> Internal Carotid A. - Passing through carotid canal - Subclavian A. -> Vertebral A. - Passing through Transverse Foramen including C1 - Internal Jugular V. -> Brachiocephalic v. -> Superior Vena Cava ## Brainstem Arteries - Vertebral A. -> Basilar A. & Posterior Spinal A. (x2) - Basilar A. gives rise to: - Posterior Cerebral A. - Superior Cerebellar A. - Pontine A. - Anterior Inferior Cerebellar A. - Posterior Inferior Cerebellar A. - Anterior Spinal A. ## Spinal Arteries and Veins - Anterior & (2x) Posterior Spinal A. - Anterior Spinal A from Basilar A and Vertebral A - Posterior Spinal A x2 from Vertebral A - Reinforced by Anterior & Posterior Medullary A. - Fed by Intercostal A. <- Aorta - Epidural Venous Plexus ## Circle of Willis - 5 arteries in total - Internal Carotid A. -> Middle Cerebral A. and Anterior Cerebral A. - Anterior Communicating A Connects bilateral Anterior Cerebrals A. - Basilar A. -> Posterior Cerebral A. - Posterior Communicating A connects middle and posterior cerebral A. ## Summary - Posterior Circulation - Vertebral A. to Basilar A. - Basilar A. to AICA, PICA, Superior Cerebellar, Posterior Cerebral, and Pontine A. - Anterior Circulation - Internal Carotid A. to Middle Cerebral, Anterior Cerebral, and Anterior Communicating - Spinal Circulation - Anterior Spinal A and Posterior Spinal A (x2) from Basilar and Vertebral A. - Reinforced by Medullary A off Intercostal A from Aorta A - Veins: Epidural Venous Plexus and Internal Jugular Vein - ...For now ## QUIZ! Circle of Willis on MRA ## Penetrating Arteries - Arteries are within the subarachnoid space - Perivascular Spaces - Arteries penetrate pia mater - Brain Capillaries are connected by tight junctions and tightly controlled - Systematic capillaries are fenestrated ## Blood Brain Barrier - Penetrating arteries are surround by glial cells forming the blood brain barrier - Astrocyte- a glial cell which maintains neurochemical environment - Blood Brain Barrier Functions: - Tight junctions controlling entry from blood - Active transport require for large molecules - Protect from infection, inflammation, and toxin - Allow free exchange: O2, CO2, and other lipid soluble substances - Astrocytes regulate using ions, neurotransmitters and hormones ## Circumventricular Organs - Exceptions to blood brain barrier allow direct sampling of blood flow and secretion neuropeptides - Contained with the hypothalamus, 3rd ventricle, and 4th Ventricle - Examples - Neurohypophysis- regulation and release of pituitary hormones - Pineal gland- melatonin production and circadian rhythms ## Imaging & Changes in Blood Flow - Auto regulation- Brain will regulate blood flow based: - Neurotransmitters, Metabolic activity, oxygen, glucose and pH - Assisted by astrocytes, circumventricular organs, and more - Glucose and Oxygen demands increase from brainstem to cortex - Brain starts shutdown higher metabolic demand regions in low resource situation - Intracranial Pressure (↑ pressure ↓ blood flow) ## Summary - Penetrating arteries enter through perivascular space and are surrounding by astrocytes - Blood brain barrier - limited exchange of large molecules through tight junctions and glial cells - Circumventricular Organs – sample the blood through specialized cells - Autoregulation – adaptive control of blood and nutrient distribution # Veins and Cerebrospinal Fluid ## Dural Sinuses - Superficial Cerebral V. -> Bridging V. -> Superior Sagittal Sinus - Within the Falx Cerebri - Drains cortex and white matter - Deep Cerebral V. -> Bridging V. -> Inferior Sagittal Sinus -> Straight Sinus - Drains basal ganglia, diencephalon, and white matter - Bridging Veins cross the meninges ## Sinus Confluence - All Sinuses come to confluence of sinuses -> Transverse sinus - Confluence at junction of falx and tentorium - Transverse sinus within the Tentorium Cerebelli - Drains into sigmoid sinus -> Internal Jugular V. ## Summary - Superficial Cerebral V. -> Bridging V. -> Superior Sagittal Sinus -> Sinus confluence -> Transverse sinus -> Sigmoid Sinus -> Interval Jugular Vein - Deep Cerebral V. -> Bridging V. -> Inferior Sagittal Sinus -> Straight Sinus -> Sinus confluence.... ## Dura Mater - Tough mother with two layers - Periosteal - adhered to skull - Meningeal- adhered to arachnoid mater - Three major folds: - Falx Cerebri - Superior Sagittal Sinus - Tentorium Cerebelli - Transverse Sinus - Falx Cerebelli ## Arachnoid Mater - Delicate membrane loosely adhered to dura - Between Arachnoid and Pia mater is subarachnoid space which is filled with CSF - Arachnoid Trabeculae- string like projections which connect arachnoid mater to pia mater - Arachnoid Granulation – clusters of arachnoid mater projecting into the sinus - Filters CSF from subarachnoid space into venous circulation ## Pia Mater - Thin cell layer adhered to the surface of the brain - NOT the blood brain barrier - Does project into cerebrum around blood vessels before then astrocytes form blood brain barrier - Denticulate ligaments- extension of pia attaching to dura mater - Anchors Laterally - Filum Terminale- extension of pia to coccyx - Anchors inferiorly - Lumbar Cistern- filled with CSF and cauda equina at base of spine ## Layers and Spaces - Skull - Epidural Space - Dura Mater (periosteal) - Dura mater (meningeal) - Subdural Space filled with sinuses and veins - Arachnoid Mater - Subarachnoid Space filled with CSF, Arteries and veins - Pia Mater ## Summary - Dura Mater- tough mother adhered to skull and arachnoid mater - Arachnoid Mater- weblike projections connecting to and forming subarachnoid space for CSF - Pia Mater- tightly adhered to surface of brain created layer between CSF and brain tissue - Epidural, Subdural, and Subarachnoid spaces ## Choroid Plexus and CSF - Choroid Plexus- Specialized cells surrounding capillaries floating within ALL ventricles - Produces CSF composed of glucose, protein, and electrolytes - Use active and facilitated transport across specialized cells - Cerebrospinal Fluid- cushions brain and spine, free nutrient and waste products exchange between CSF and extracellular space, homeostasis, and pressure regulation ## Lateral Ventricles - Paired within right and left hemisphere - Anatomy- anterior horn, posterior horn, inferior horn and atrium - Each connects directly to 3rd ventricle through interventicular foramen of Monroe ## Third and Fourth Ventricle - Third Ventricle - Anatomy: Between the two thalami and pierced by interthalamic adhesion - Connect to 4th ventricle by Cerebral Aqueduct of Slyvius - Fourth Ventricle - Anatomy: Posterior to brainstem and anterior to cerebellum - Connects to subarachnoid space through Foramen of luscke (x2) and Foramen of Magendie - Connects with central canal of spinal cord on posterior pons - Both have choroid plexus and circumventricular organs to sample blood ## Ventricles - Choroid Plexus is floats freely in all ventricles producing CSF through specialized capillaries - CSF follows through each lateral ventricle, the 3rd and 4th ventricle then out into the subarachnoid space surrounding the brain and spine. - It is resorbed by arachnoid granulations into venous circulation within the sinuses.