Flashcards in Blood Supply Deck (20)
What supplies most of cerebrum?
What are its branches?
What does it bifurcate into?
internal carotid arteries
branches: opthalmic artery, anterior choroidal artery, posterior communicating artery
bifurcates into the anterior and middle cerebral artery
What supplies the brainstem, cerebellum, and spinal cord?
What are the branches?
Vertebral branches - posterior and anterior spinal artery, posterior inferior cerebellar artery (PICA)
What do vertebral arteries fuse to form?
What are the basilar branches?
What does do the vertebral arteries bifurcate into?
fuse to form basilar artery
basilar branches- anterior inferior cerebellar artery (AICA), superior cerebellar artery
bifurcates into posterior cerebral arteries
What is the Circle of Willis?
interconnects the anterior and posterior circulations
also intracranial-extracranial anastamoses (external-internal carotid artery, carotid-basilar, carotid-vertebral)
What supplies deep cerebral structures?
small perforating arteries
arteries around base of brain - give rise o small perforating (or ganglionic) arteries
What are the MCA branches?
supplies the deep structures of diencephalon, hypothalamus, and telencephalon
Describe the drainage of cerebral veins.
Cerebral veins drain
dural venous sinuses
internal jugular veins and basilar venous plexus (base of the brain, communicates with epidural venous plexus of spinal cord)
Describe the two major divisions of the cerebral venous system.
superficial veins :
superior group - empty into superior and inferior sagittal sinuses
inferior group - empty with transverse and cavernous sinus
Describe the cerebral venous system in regards to the cerebellar and brainstem.
Collection of veins that drain into the deep (Great vein of Galen), straight, transverse and petrosal sinus
Describe the control of blood flow to the CNS.
2 percent of body weight
15 percent cardiac output
25 percent oxygen consumption
Describe the flow rate of blood to CNS.
normally 55mL of blood/100g CNS/minute
20 ml- neurons stop generating electrical signals
10ml- necrosis of brain
Describe autoregulation (control of blood flow to CNS).
arterial and smooth muscle cell mediated
Describe metabolic (control of blood flow to CNS)
increased neuronal activity - glutamate released - astrocyte end feet receptors activated - vasodilator factors released at end-feet applied to vessels
What is the Blood Brain Barrier (BBB) "neurovascular unit"
restricts ionic/fluid movements, supplies essential nutrients, mediates efflux of waste or toxic products
What brain barriers are there?
blood-spinal cord barrier
blood nerve barrier
blood retinal barrier
blood labyrinth barrier
Describe the blood-brain barrier composition.
capillary endothelial cells
pericytes, astrocytes and neuronal processes
What are the entry points for perforating arteries? Where are they?
anterior and posterior perforated substance - visible entry points of perforating arteries on base of the brain
Describe cerebral veins.
valveless with numerous anastamoses
What do emissary veins do?
they connect extracranial veins with dural sinuses.