Nolte – Chapter 6 (Blood Supply of the Brain) and all Class-Notes and Lab-Notes tagged with
Chapter 6.
Internal Carotid (80%-telencephalon and diencephalon) and Vertebral (20% cerebellum and
brainstem) arteries supply all of the brain.
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Internal Carotid
o supplies the eye by way of the opthalamic artery
o Sits superior to the optic chiasm
o Pre-Bifurcating branches.
 anterior choroidal
 optic tract, choroid plexus, internal capsule, thalamus,
hippocampus
 posterior communicating artery
 joins the posterior cerebral artery
o Bifurcation
 middle cerebral
 insula
 most of the lateral surface of the cerebral hemisphere.
o an occlusion would mess up most of the body, but not the
legs (from a motor and sensory perspective)
 lenticulostrate branches (perforating arteries)
o deep cerebral structures like the basal ganglia
 anterior cerebral
 both hemis get joined temporarily by the anterior communicating
artery
 curves around the corpus collosum and, at the genu, gives off the
callosomarginal and pericallosal artery
 follows corpus collosum and supply medial parts of the frontal
and parietal lobes
o motor speaking, occulision of this would affect the legs
(since that’s the part of the pre and post central gyri that
come medial on the somatic map)
Vertebral Arteries
o Pre-Basal branches
 posterior spinal
 spinal cord caudal
 anterior spinal
 spinal cord anterior
 posterior inferior cerebellar(PICA)
 inferior surface of the cerebellum
 lateral medulla
 choroid plexus of the 4th ventricle
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o Two vertebral combine into the Basilar Artery
 Prebifurcation
 anterior inferior cerebellar(AICA)
o anterior portions of the inferior surface of the
cerebellum(flocculus)
o caudal pons
 superior cerebellar
o superior surface of cerebellum
o rostral pons and caudal midbrain
 Bifurcation
 posterior cerebral arteries
o this get an extra fuel from the internal corotid’s posterior
communicating artery.
o supply medial and inferior surfaces of the occipital and
temporal lobes
 would lead to visual field losses
Circle of Willis
o posterior cerebral artery is connected to the internal carotid by the posterior
communicating
o the anterior communicating(connecting the two anterior cerebral at a junction)
finishes the circle.
o if one major vessel becomes occluded either within the circle of Willis or
proximal to it, the communicating arteries may allow critically important
anastomotic flow and prevent neurological damage
Blood Vessel
o innermost is the luma, then internal elastic lamina, then smooth muscle, then
adventitia layer
Blood Flow
o autoregulation
 act to maintain constant flow
 vessels will constrict(increase resistance) in response to increased blood
pressure
 they relax in response to decreased pressure.
o indicative of increased synaptic activity, which causes the release of glutamate
that then reaches nearby astrocyte end-feet which can then release vasodilating
factors (prostaglandins and NO).
Injuries
o necrotic region is known as an infarct
o ischemic strokes
 a thrombus(blood clot) and an embolus(foreigh matter- part of a blood
clot or plaque) causes an occlusion of an artery supplying the brain.
 if near circle of willis, adequare collateral circulation can happen.
if not…less likely
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o tiny lesions are lacunes
o profound iscemial repifly depletes the energy stores of neurons and they
depolarize and release excitatory neurotransmitters in a destructive cascade
 usually is surrounded by a penumbra (shodow region)
o intracerebral hemorrhage is a type of stroke that is the rupture of small
perforating arteries such as the lenticulostriate (part of the middle cerebral)
o aneurysms
 balloon like swellings of arterial walls
 can push against brain regions like a tumor.
 can cause a subarachnoide hemorrhage if they rupture
o arteriovenous malformation
 large anastomoses between arteries and veins and steal blood from
normal tissue
The Blood Brain Barrier
o extracellular fluid of the body to the extracellular fluid of the brain
o includes the arachnoid barrier layer and the blood-CSF barrier
o also includes the true blood-brain barrier
 tight junctions between adjacent endothelial cells of cerebral capillaries
together with a lack of pinocytotic
o lipid soluble substance can diffuse across and glucose can cross it by a process of
facilitated diffusion.
o substances can be actively transported across this endothelial wall.
o pituitary gland can freely interact with the blood like the choroid plexus
o Other regions can monitor the composition of extracellular flui and project axons
Veins
o cerebral veins empty into the dural venous sinuses and lead into the interal
jugular veins and into the basilar venous plexus
 this communicates with the epidural venous plexus.
o Veins are either superficial or deep
 superficial are on the surface of the hemispheres and empty into the
superior saggital sinus
 uperficial middle cerebral runs along the lateral sulcus and drains
the temporal lobe
 superior anastomotic vein travels across parietal and connects the
middle with the superior sagittal sinus.
 inferior anastomotic vein is the posterior and inferior temporal
love
 deep veins drain internal sutrctures and empty into the straight sinus.
 internal cerebral vein drains the thalamus and caudate
o its branch the thalmostriate is joined by the choroidal vein
which drains the choroid plexus
o internal cerebral veins bend sharply at a “Venous angle” at the location of the
interventricular foramen
o The great vein takes the internal cerebral veinsthrough the transverse cerebral
fissure in the superior cistern and goes to form the straight sinus.
 its also joined by the basal veins which is formed near the optic chiasm
and gets joined by the deep middle cerebral vein that drains the insula.