Blood Supply to CNS

vertebral artery

enters the skull through the foramen magnum after coursing posteriorly over C#1

• 20% blood flow to brain

• provides blood to the BRAINSTEM

internal carotid artery

ascends in the lateral part of the neck to reach the base of the skull

• enters the skull through carotid canal located below the cavity of middle ear

• 80% blood flow to brain

• supplies blood to CEREBRAL CORTEX

posterior inferior cerebellar artery

posterior spinal artery

anterior spinal artery

direct branches of vertebral artery

posterior inferior cerebellar artery

provides blood to the caudal, medial portion of the cerebellum

anterior spinal artery

the paired arteries anastamose to form a single blood vessel

aneurysm

bulging in the wall of the vessel caused by weakening of the wall

basilar artery

the right and left vertebral arteries anastamose to form this artery; supplies blood to the pons and rostral cerebellum

anterior inferior cerebellar artery

pontine arteries

superior cerebellar artery

direct branches of basilar artery

anterior inferior cerebellar artery

provides blood to caudal lateral portion of the cerebellum

superior cerebellar artery

supplies blood to the rostral portion of the cerebellum

posterior cerebral artery

supplies blood to the midbrain and ventral,medial portions of the temporal and occipital lobes

anterior cerebral artery

anterior communicating artery

middle cerebral artery

posterior communicating artery

branches of the internal carotid artery

anterior cerebral artery

supply blood to medial surface of the cerebral cortex - medial surface of frontal, parietal and cingulate cortex

anterior communicating artery

connects the right and left anterior cerebral arteries

middle cerebral artery

supply blood to the lateral portion of the cerebral cortex

• lateral surface of frontal, parietal and temporal lobes

posterior communicating artery

connects the vertebral artery blood system with the internal carotid blood system

• join the middle cerebral artery with the posterior cerebral artery

lenticulostraite arteries

branches of middle cerebral artery that supply blood to nuclei deep in the cerebral cortex

• nuclei are part of the basal ganglia (motor system)

circle of willis

anastomatic connection between the vertebral/basiliar artery system and internal carotid artery system, allowing for collateral circulation

subarachnoid hematoma

occurs when blood vessels on the surface of the brain rupture - causes blood to be released into subarachnoid space

• causes extensive neurological damage due to loss of blood as well as contact of brain tissue with the blood

dura mater

arachnoid

pia mater

meninges of the brain

periosteal layer

dural border cells

2 layers of the dura mater

periosteal layer

adheres to the inner surface of the skull; layer ends at the foramen magnum - not present on spinal cord

dural border cells

innermost layer; loose arrangement, provides potential plane of separation between dura mater and arachnoid - location of subdural hematomas

barrier cells

trabeculde in subarachnoid space

two layers of arachnoid

pia mater

intimately applied to the surface of the brain and spinal cord following all contours; surround blood vessels

dural folds

infoldings of the inner layers of the dura mater

falx cerebri

tentorium cerebelli

falx cerebelli

three dural folds:

falx cerebri

midline projection of dura that separates two central hemispheres; fuses at right angles with tentorium cerebelli on midline superiorly

tentorium cerebelli

horizontal fold of the dura that separates the cerebellum from the occipital love; contains the tentorial notch t

tentorial notch

where the brainstem passes through

falx cerebelli

small projection that separates two hemispheres of cerebellum; fuses at right angles with the tentorium cerebelli on midline inferiorly

dural sinuses

openings between periosteal and dural border cells; represent the major routes by which venous blood is drained from the brain

superior sagittal sinus

inferior sagittal sinus

straight sinus

occiptal sinus

transverse sinus

sigmoid sinus

cavernous sinus

sinuses of the brain

superior sagittal sinus

formed on the upper edge of the falx cerebri; drain blood Rostral to Caudal

inferior sagittal sinus

formed on the lower edge of falx cerebri

confluence of sinuses

superior sagittal, inferior sagittal, straight and occiptal sinuses converge at this point

transverse sinus

joins the sigmoid sinus and the confluence of sinuses to drain the blood to the jugular foramen and the internal jugular vein

cavernous sinus

venous blood from orbit, nasal cavity and rostral brainstem drain into here

epidural hematoma

bleeding between bone and outer later of dura

• lens shape on CT

• compresses underlying neural tissue

subdural hematoma

between inner layer of dura and outerlayer of arachnoid

• crecent shape

• occurs due to tear in cerebral vein as it is draining into one of the sinuses