Blood Supply of the CNS

Lecture Objectives Describe the four arteries supplying the CNS. Follow up each artery to its destination. Describe the circle of Willis and its branches. Discuss the principle of end artery type of circulation. Describe venous drainage of the brain.

Vertebral Artery Branch of the 1 st part of the subclavian a. Ascends the neck through the upper sex transverse vertebrae Inters the skull through foramen magnum Both sides unit to form the basilar a.

Branches Meningeal aa. Anterior spinal a. Posterior spinal aa. Posterior inferior cerebellar a. Medullary aa. Vertebral Artery

Basilar Artery Ascend in front of pons Participate in forming circle of Willis Branches Anterior inferior cerebellar aa. Pontine aa. Superior cerebellar aa. Posterior cerebral aa. (end branches) Inferior & posterior parts of cerebrum

Blood Supply to Cortex Circle of Willis

Blood Supply to Cortex Vascular Territories

Blood Supply to Deep Structures

Internal Carotid Artery Ophthalmic a. Posterior communicating a. Anterior choroidal a. Anterior cerebral a. Middle cerebral a.

Middle Cerebral Artery Language areas (left MCA in most people) Motor & somatosensory cortex (except lower limb & perineum) Auditory cortex Lenticulostriate arteries basal gangila & internal capsule (genu)

Middle Cerebral Artery

Anterior Choroidal Artery Hippocampus, uncus & amygdala Choroid plexus (temporal horn of lateral ventricle Globus pallidus, putamen, part of thalamus Internal capsule (posterior limb)

Anterior Choroidal Artery

Anterior Cerebral Artery Motor & somatosensory cortex (lower limb & perineum) Corpus callosum (except splenium) Olfactory bulb & tract Recurrent artery of Heubnar Head of caudate (ventral part) and adjacent putamen Internal capsule (anterior limb)

Anterior Cerebral Artery

Posterior Cerebral Artery Hippocampus Parahippocampal gyrus Calcarine branch all primary & some association cortex for vision Posterior choroidal artery Choroid plexus (lateral & 3 rd ventricles) Thalamus (posterior part) Fornix Tectum

Posterior Cerebral Artery

Blood Supply to SC One anterior spinal a. Vertebral aa. Two posterior spinal aa. Vertebral aa. 25% PICA 75% Anterior & posterior radicular aa. Arise at every spinal level Serve their respective roots & ganglia

Anterior & posterior spinal medullary aa. Arise at intermittent levels Serve to augment the BS to SC Artery of Adamkierwicz Unusually large spinal medullary a. Usually on the left In low thoracic or upper lumber levels Blood Supply to SC

Spinal cord Ischemia Anterior spinal a. Small & tenuous Occlusion produces bilateral damage (below lesion) Affects Corticospinal tracts Paraplegia below lesion Spinothalamic tracts Thermoanesthesia and analgesia Descending autonomic tracts Loss of bladder & bowel control Anterior gray horn Near enlargement weakness of limb muscles Blood Supply to SC

Veins of the Brain Superior cerebral veins SSS Superficial middle cerebral veins cavernous sinus Thalamostriate vein Choroid vein Deep middle cerebral vein Anterior cerebral Striate veins basal vein Internal cerebral vein Great cerebral vein straight sinus External cerebral veins Internal cerebral veins

Veins of the Brain

Dural Venous Sinuses Location Drains.. Fate Superior sagittal sinus Venous lacunae Inferior sagittal sinus Straight sinus Occipital sinus Transverse sinus Sigmoid sinus Cavernous sinuses Superior and inferior petrosal sinuses

Dural Venous Sinuses

Blood Brain Barrier protects cells from some toxins and pathogens proteins & antibiotics can not pass but alcohol & anesthetics do Structure tight junctions seal together epithelial cells continuous basement membrane astrocyte processes covering capillaries

Blood Brain Barrier Areas without BBB Area postrema in the floor of the fourth ventricle Areas in the hypothalamus Structure Endothelial fenestrations

Blood Cerebrospinal Fluid Barrier Structure Endothelial cells BM of endothelial cells Pale cells BM of choroidal epithelial cells Tight junctions seal the choroidal epithelial cells