Vasculature of CNS Flashcards
two routes to get blood to cranial vault
internal carotid arteries 2x left and right
vertebral arteries 2x left and right
internal carotid system
enter skull at carotid canal
join cerebral arterial circle
branches of cerebral arterial circle
three cortical branches
off of these three - deep perforating branches
branches of internal carotid
middle cerebral a.
posterior communicating a.
anterior cerebral a.
lenticulostriate arteries
deep penetrating arteries
lentiform and striatum nuclei (basal nuclei)
branches of middle cerebral arteries
anterior cerebral artery
runs in longitundinal fissure and above corpus callosum
left and right 2x
corpus callosum
connects L and R cerebral hemispheres
vertebral arteries
enter cranium vault via foramen magnum
-meet as basilar artery
basilar artery
where vertebral arteries come together
branches of basilar artery
posterior cerebral arteries
posterior inferior cerebellar artery
first large branch off of vertebral arteries
-serves posterior / inferior cerebellum
anterior inferior cerebellar artery
second large branch off of vertebral arteries
superior cerebellar artery
branch off of basilar artery
pontine arteries
branches of basilar artery
-blood to pons
posterior spinal artery
arises off of vertebral artery or posterior inferior cerebellar artery
anterior spinal artery
single artery that arises from both vertebral arteries
blood brain barrier
physiologic barrier between intravascular space and CNS ECF
in brain and spinal cord
two major types of capillaries
continuous and fenestrated
continuous capillaries
in CNS
no pores or fenestrations
tight junctions between endothelial cells
endothelial cells lining capillaries that form blood brain barrier
components of blood brain barrier
capillary lined by endothelial cells (continuous)
-tight junctions between them
astrocyte end feet
-do NOT form blood brain barrier
what can cross blood brain barriers
small molecules (< 400 daltons) insulin - 6,000 daltons - cannot pass without transporter
also, gas can diffuse and lipid soluble mlcs
ventricular space
fluid filled spaces within brain
developmental remnant of neural tube
4 in brain - continuous with central canal to SC
subarachnoid space
continuous with the ventricles of brain
surrounds brain and spinal cord
fluid filled
choroid plexus
site of CSF production
ventricle lining
ependymal cells
-ciliated and can move fluid
ventricles
2x lateral
third ventricle
fourth ventricle
lateral ventricle division
anterior horn body posterior horn inferior horn trigone
interthalamic adhesion
in third ventricle
-connecting left and right thalamus
aqueduct of midbrain
from third ventricle to fourth ventricle
aka mesencephalic aqueduct
apertures
openings in 4th ventricles to subarachnoid space
separation of lateral ventricles
septum pellucidum
central canal
continuous with fourth ventricle
to spinal cord
connection of lateral and third ventricle
interventricular foramen 2x
boundaries of lateral ventricles
roof - corpus callosum floor - diencephalon lateral walls - caudate nucleus** roof of inferior horn - tail of caudate nucleus floor of inferior horn - hippocampus
boundaries of third ventricles
lateral walls - diencephalon
floor - optic chiasm and infundibulum
mesencephalic aqueduct
no choroid plexus - no CSF production
good site for occlusion
boundaries of 4th ventricles
roof - cerebellum
floor - pons/medulla
openings of subarachnoid space
from 4th ventricle
1x median
2x lateral
CSF
produced from blood
protects CNS - buoyancy (decreases weight) and serve as ECF
also a possible lymphatic function
pH influence on respiratory centers
CSF production
active - uses ATP to transport ions
passive - water follows ions
selective - pick out constituents in blood we want
500mL / day
reabsorption of CSF
passive - dependent on pressure gradient
choroid plexus
roof of every ventricle
-2x lateral, third, fourth
choroid epithelium
continuous with ependymal cells lining ventricles
-modified ependymal cells
has tight junctions
forms blood CSF barrier
capillaries to choroid plexus
surrounded by choroid epithelium
fenestrated capillaries
anterior choroidal artery
main artery supplying choroid plexus
free exchange
between capillary and choroid epithelium
arachnoid granulations
reabsorption of CSF to venous sinus system
have one way valves - pressure dependent
hydrocephalus
CSF production is active
-independent of pressure
water in brain
-occlusion of CSF flow
occlusion of interventricular foramen
results in huge lateral ventricles
hydrocephalic shunt
drain CSF - commonly to peritoneum for absorption
