Presentation on theme: "Blood supply to the brain The cerebrospinal fluid (CSF) Mark Kozsurek, M.D., Ph.D. 19/09/2011, EM II."— Presentation transcript:
Blood supply to the brain The cerebrospinal fluid (CSF) Mark Kozsurek, M.D., Ph.D. 19/09/2011, EM II.
Extremly high demand for oxygen and nutrients: human brain represents 2% of the body weight, but receives 15% of the cardiac output, 20% of total body oxygen consumption and 25% of total body glucose utilization. Cerebrovascular deseases and stroke are among the major causes of death.
oculomotor n. abducens n. optic chiasm mamillary bodies pituitary stalk
1.Circle of Willis encloses the optic chiasm, pituitary stalk and mamillary bodies. 2. Oculomotor nerve exits between the post. cerebral and sup. cerebellar arteries. 3. Vertebral arteries of the two sides unite to form the basilar artery at the ponto-medullary junction. The root of the abducens nerve and initial segment of the ant. inf. cerebellar artery can also be found here.
ant. cerebral deep middle cerebral basal (Rosenthal) great cerebral (Galen) DEEP VEINS
of septum pellucidum thalamostriate choroid * int. cerebral great cerebral
ant. cerebral deep middle cer. basal v. of septum pell. thalamostriate choroid internal cerebral great cerebral vein
Almost the total volume of veinous blood collected from the brain leaves the skull through the jugular foramen and the internal jugular vein. If the jugular foramen and/or the internal jugular vein is getting occluded, blodd may escape through the diploic and emissary veins connecting the dural sinuses with the veins of the scalp skin.
Diploic veins (frontal, anterior and posterior temporal, occipital): form a network between the external and internal compact bony layers of the skull and connect dural sinuses with the external veins.
Emissary veins (occipital, parietal, condylar, mastoid): pearce the skull directly and connect dural sinuses with external veins. diploicemissary
Blood-brain barrier (BBB) The extracellular fluid of the CNS is separated from the blood by the BBB ensuring strictly controlled and mainly carrier protein assisted transport of macromolecules. Is formed by endothelial cells attached to one other by tight junctions, basement membrane, astrocytic endfeet. Protects the CNS from possibly toxic agents but makes development of medicines acting on the CNS difficult (e.g. antibiotics in infections).
Life outside the BBB: the circumventricular organs „Circumventricular” = around the ventricles Incomplet or missing BBB Highly capillarized structure Secretion of neurohormons or detection of hormons, glucose, ions, etc.
Subfornical organsensoryfluid regulation Organum vasculosum sensory, secretory detects peptides, fluid regulation Median eminencesecretory regulates the anterior pituitary through the release of neurohormones Neurohypophysissecretory store and secretes the hormones oxytocin and ADH into the blood, but does not synthesize either hormone Subcommissural organ secretory secretes certain proteins into the cerebrospinal fluid, its specific function is as yet unknown. Pineal glandsecretory stimulated by darkness to secrete melatonin and is associated with circadian rhythms Area postremasensory the vomiting centre of the brain (can detect noxious substances in the blood and stimulate vomiting in order to rid the body of these toxic chemicals)
The cerebrospinal fluid (CSF) Provides mechanical protection for the brain and the spinal cord. When floating in the CSF brain weights only 50g (!) according to the Archimedes’ principle.
internal and external CSF spaces internal = ventricles external = subarachnoidal space
Surface of a choroid plexus
ant. choroidal from ICA or MCA post. choroidal from PCA choroidal a. of the 4th ventricle from pica
median aperture of Magendi cerebellomedullary (or great) cystern lateral aperture of Luschka lateral pontine (or pontocerebellar) cystern
Site of CSF resorption: arachnoid granulations in the superior sagittal sinus and lateral lacunae.