Blood supply of the brain Flashcards
importance of blood to the brain
- The adult brain requires 750 mL(1 quart) of oxygenated every minute to maintain normal activity
- 20% of arterial oxygen is consumed by the brain
- Cessation of blood flow for 5-10 sec temporarily changes neural activity
- As little as 5 minutes without blood flow to the brain can cause irreversible neuronal damage
Blood to the Brain is Carried out by 2 Pairs of Arteries
•Internal Carotid –“Anterior Circulation” •75% of CVAsoccur here (strokes) •Vertebral –“Posterior Circulation”
Internal Carotid Artery Carries the Anterior Circulation
•One of the two terminal branches of the common carotid
•It has cervical, petrous, cavernous, and cerebral parts
–The cerebral part gives off the ophthalmic artery
•Terminates by dividing into ACA and MCA
gives off hypophyseal artery
foramen lucerum ICA
is where it gets all funky
cavernous ICA
region where occulomotor nerve runs also
internal carotid branches
–Anterior Cerebral –Middle Cerebral –Ophthalmic –Hypophyseal –Anterior Choroidal –Posterior Communicating
Anterior cerebral artery
ACA covers medial surface of the cerebral cortex
Recurrent artery of Heubner, goes inside the brain to the subcortical
middle cerebral artery
75% of lateral surface is covered by the medial artery
Lencticulostriate
lateral surface of frontal parietal and temporal lobe
what artery has branches in the isle of reil
MCA
arteries of sudden death
MCA and ACA gives rise to
lateral lentidulostriate
medial lenticulostriate
Vertebro-basilar system
most likely to have a surviving stroke in anterior circulation
posterior circ has arteries going to brainstem and you die if you stop it
Basilar artery
ends by dividing into the posterior cerebral arteries(PCA) at the superior end of the pons. The basilar artery also gives
–superior cerebellarartery
–pontinearteries
–labyrinthine artery
–anterior inferior cerebellar artery (AICA)
labyrinthine artery
can come from a lot of places
goes to inner ear, vesitbular apparatus and cochlea
vertebral arteries
Vertebral arteries enter the foramen magnum and unite at the caudal end of the pons to form the basilar artery
posterior circulation
Circle of Willis Connects the Anterior and Posterior Circulations
Also, helps prevent complete blockage if one area is blocked
–Internal carotid artery circulation can use contralateralcirculation
But only about ½ these circles look like they do. Lots of anatomical variation here.
posterior cerebral
basilar branch
supplies mostly medial portion or temporal and occipital
supplies ventral surgace of temporal lobes and crus cereri (carries upper motor neurons) or cerebral pudencles of midbrain
thalamoperforating arteries
from pca also supply the thalamus
radicular arteries
supply spinal cord
artery of adamkiewicz
great ventral radicular artery
most important radicular
lateral lenticulostriates
from mca
lenticulostriates
supply basal ganglia
medial lenticulostriates
from aca
thalamoperforating arteries
from posterior cerebral
midbrain is supplied by
posterior cerebral
soft spots in arteries
come from where the artery changes or branches
good chance of hemorrhage
cerebrovascular accidents are concentrated
at branchpoints in ant circulation
infarct (umbra)
necrosis of tissue due to lack of blood supply uncontrolled cell death black on ct beyond repair from stroke
prenumbra
peri-infarct zone apoptosis controlled cell death possible recovery grey still have hope from stroke
symptoms from aca stroke
weakness and paralysis opposite and lower half of body
bladder dysfunction
aca stroke around corpus colloum
can you drive with one eye open?
symptoms from pca storke
occipital lobe
cant see contralaterally
hemianopsia
mca stroke symptoms
hemiparesis (with or without hemisensory deficit) mainly affecting the arm and face wernickes aphasia
angiography
suspected stroke or hematoma
increase neural activity
increase metabolism, see by glucose uptake (PET) or o2 uptake (fMRI)
the bold signale
fMRI, blood oxygen diff.
inactivated at first then activate and see the difference
BBB
- controls molecular traffic, keeps out toxins
- contributes to ion homeostasis for optimal neural signaling (main reason so ap do not get messed upped
- maintains low protein environment in CNS, limits proliferation, preserves neural connectivity
- separates central and peripheral neurotransmitter pools, reduces cross-talk, allows non-synaptic signaling in CNS
- allows immune surveillance and response with minimal inflammation and cell damage.
what can get through bbb tight junctions
oxygen
where is bbb?
capillaries
corpus callosum
arachnoid
tancytes
specialized ependymal cells that line the ventricles around CVOs
parts w/0 bbb overview
so we can detect toxins, cell conc, o2, measure things in blood.
sometimes open sometimes not
areas w/o bbb
- subfornical organ - blood osmolarity
- organ vasculosum - salt
- median eminence - hormones
- area postrema - hormones, detects toxins, vomiting
venous drainage of brain
- Thin-walled vessels in the subarachnoid space with no valves or muscle layer.
- Pierce the arachnoid mater and meningeal layer of the duramater to drain into the duralvenous sinuses.
trolard
connect the superior and inferior sagittal sinus’
labbe
drains into the transverse sinus’
superficial cerebral veins drains into the
superior saggital sinus
deep cerebral veins drain into
straight sinus
internal cerebral vein
deep veins drain here thento great cerebral vein of galen
basal vein
ACTUALLY a superficial vein. HUGE variations in venous anatomy (hypoplasias)…most consistent in the deep cerebral veins
venous drainage of medial cortex
Thalamostriate-septal meet internal c v at the venous angle, providing a landmark..Basal vein connects cavernous sinus and spheonparietal sinus to great vein of gale—straight sinus
superior petrosal veins
on lateral cerebellum drain to transverse sinus
pontine veins
anteromedian, anterolateral, and transverse
spinal cord veins
anterior and posterior spinal and radicular veins
