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40 Cards in this Set
- Front
- Back
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Why is blood supply important for the brain and what happens if it is deprived of it?
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The brain can't store oxygen or glucose, yet it is very metabolically active. It must receive a constant supply of well oxygenated blood with lots of glucose.
Deprevation leads to damage. After 10 sec. of brain ischemia there is unconsciousness. After 20 sec. electrical activity ceases and after a few minutes, irreversible damage begins. |
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Desribe the path of the internal carotid arteries prior to dividing into the several branches in the brain.
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Enters the middle crainial fossa via the carotid canal and makes a sharp hair pin turn forward, then superiorly and then posteriorly. Gives off HYPOPHYSEAL artery to the pituitary gland and the OPHTHALMIC artery, passing thru the optic foramen into orbit, supplying the eye. It then gives off a ton of other branches.
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What are the final branches off of the internal carotid arteries in the brain?
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The medial and anterior cerebral arteries.
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What artery does the internal carotid artery come off of?
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The common carotid artery
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What are the brances of the internal carotid artery in the neck?
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There are none!
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What are the branches off the internal carotid arteries prior to ending with the medial and anterior cerebral arteries.
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Anterior choroidal artery, posterior communicating a., pericallosal a., callosomarginal a., and lateral striate a.
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What does the anterior choroidal artery supply and whre is it located?
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Supplies optic tract and travels with it. Also supplies thalamus and hippocampus. Is often involved in a stroke.
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Where is the posterior commuincating artery located?
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Coming off of the internal carotid artery, it passes posteriorly, inferior to the optic tract to join up with the posterior cerebral artery.
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Where is the anterior communicating artery located and what does it do?
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Between the two hemispheres, connecting the two anterior cerebral arteries from each hemisphere.
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What does the anterior cerebral artery supply and where does it run?
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Supplies the medial surface of the hemispheres via entering the longitudinal fissure. The anterior cerebral arteries from each hemisphere join via the anterior commuincating artery.
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What are two branches off of the ant. cerebral artery?
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1. Pericallosal
2. Callosomarginal |
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Where is the middle cerebral artery and what does it supply?
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Comes directly off of internal carotid artery into the lateral sulcus and supplies most of the LATERAL surface of the cerebral hemisphere. Occulsion of this artery causes major motor and somatosensory deficits.
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What are lateral striate arteries? Also called lenticulostriate arteries.
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Perforating or ganglionic arteries off of the middle cerebral artery. Very small branches that penetrate the brain near their origin and supply deep structures of the diencephalon and telencephalon.
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What are Ganglionic branches of the lateral striate arteries?
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Small branches off arteries around the base of the brain collectively referred to as "ganglionic"
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Where are the vertebral arteries? And what do they form?
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The vertebral arteries are joined at the junction of teh pons and the medulla. They form the basilar artery.
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The vertebral arteries give off 3 branches before uniting to form the basilar artery. What are they?
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1. Anterior spinal a.
2. Posterior spinal a. 3. Posterior inferior cerebellar artery (PICA). |
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The basilar artery gives off 3 branches...what are they?
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1. Anterior inferior cerebellar artery.
2. Superior cerebellar artery 3. Posterior cerebral artery. |
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Where is the anterior inferior cerebellar artery located? What does it supply?
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Arises just below (rostral) to the origin of the basilar artery. It supplies the anterior portions of the inferior cerebellum.
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Where is the superior cerebellar artery? And what is it a branch off of?
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Comes off of the basilar artery just caudal to it's orign and goes to each side of the cerebellum, supplying the superior surface.
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Where is the posterior cerebral artery located?
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A bifrication of the basilar artery, it divides just caudal of the superior cerebellar arteries at midbrain level.
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The post. cerebral a. gives off a branch, what is it and where is this branch located?
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The branch is the posterior choroidal artery. The ant. and post. choroidal arteries form anastomoses.
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What is the Circle of Wilis?
When will it work and when will it not work? |
A circle of blood vessels that help re-route blood if there is an occulsion. The occulsion HAS to be PROXIMAL to the circle, closer to the heart, for the circle to have significance and preserve the brain tissue. A normal circle is present in about 50% of people. There are lots of varients though. The circle will work good if blockage is slow, but not good if blockage is fast. Ex. Circle will not work if block is in middle cerebral artery, because it is not proximal to the circle.
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What arteries make up the Circle of Willis?
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Internal carotid, ant. cerebral, ant. communicating, post. communicating and post. cerebral arteries. (Remember that all these arteries exist on each side)
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Aside from the circle of Willis, where do alternate blood flow routes occur?
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There is anastomosing btwn terminal branches of the cerebral arteries (MCA w/ ACA). The ant. and post. choroidal arteries can also anastomoses.
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How would you describe the control of cerebral blood flow?
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Normally maintained at a constant rate. Increases/decreases as parts of brain are being used. Correlates with neural activity.
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There are three mechanisms of cerebral blood flow?
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1. Autoregulation
2. Response to metabolites 3. Cerebral blood vessels are innervated. |
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Describe autoregulation as a mechanism for cerebral blood flow.
What is the rxn to changes in BP? |
Blood vessels will act to maintain constant blood flow.
Increase in BP = vessels constrict Decrease in BP = vessels dialte |
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Describe the response to metabolites as a mechanism for cerebral blood flow.
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Increase in CO2 = dilation of blood vessels = increased blood flow (to rid themselves of this buildup)
Decrease in CO2 = blood vessels constrict = decrease in blood flow Increase in 02 = blood vessels will constrict = decreased blood flow Decrease in 02 = blood vessels will dilate = increasd blood flow |
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Describe the innervation of the cerebral blood vessels.
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They are innervated by both sympathetic and parasympathetic fibers. Neural control of teh blood flow is not very important.
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What is the route of venous drainage?
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cerebral veins drain into dural sinuses which drain into internal jugular veins.
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What connects extracranial veins with dural sinuses?
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Emissary veins
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Where are the superficial veins located and where do they drain into?
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Located on the surface of the hemispheres and drain into the superior sagittal sinus.
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Where are the deep veins located and where do they drain into?
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Located in deep structures of the brain and drain into the straight sinus.
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What are three characteristics of cerebral veins?
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1. No valves
2. They are variable 3. Connected by rich anastomoses. |
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Where does the middle cerebral artery run?
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Laterally into the lateral fissure and then wraps around the lateral surface of the hemispheres.
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What artery(s) supply the deep structures of teh telencephalon and diencephalon?
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Lateral Striate Arteries, which are off of the middle cerebral artery.
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What type of artery supplies deep structures of the brain?
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Ganglionic or perforating arteries.
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Where are ganglionic/perforating arteries abundant?
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Around the optic chiasm and cerebral peduncles.
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What are the anterior and posterior perforated substances?
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Ganglionic or perforating arteries around the optic chiasm and cerebral peduncles.
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Where is CSF resabsorbed?
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In the arachnoid villi located in all of the sinuses and caudally along the dura of the proximal nerve root.
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