Blood supply Flashcards
What major area does the internal carotid a. supply?
Most of cerebrum
What does the ICA bifurcate into?
Anterior and middle cerebral aa. (ACA, MCA)
What are the major branches of the ICA (ACA + MCA)?
- Ophthalmic a.
- Anterior choroidal a.
- Posterior communicating a. (PCoA)
What major area does the vertebrobasilar a. supply?
Brainstem, cerebellum, sc
What do the vertebral aa. fuse to form?
Basilar a.
What are the major vertebral branches of the vertebrobasilar a?
- Posterior inferior cerebellar a. (PICA)
- Posterior spinal aa.
- Anterior spinal a.
What are the major basilar branches of the vertebrobasilar a?
Basilar:
- Anterior inferior cerebellar a. (AICA)
- Superior cerebellar a. (SCA)
What does the basilar a. bifurcate into?
2 Posterior cerebral aa. (PCA)
What are the roots of the anterior, middle, and posterior cerebral aa.?
ACA: ICA
MCA: ICA
PCA: Basilar a.
Generally, what does circle of Willis interconnect?
Specifically?
- Anterior and posterior cerebral circulations
- Connects ACA to each other (via ACoA), MCA to PCA (via PCoA)
What types of aa. supply deep cerebral structures?
Small perforating (ganglionic) aa. at base of brain
What supplies the deep structures of the diencephalon, hypothalamus, and telencephalon?
MCA branches known as lenticulostriate aa.
AKA anterolateral central aa.
What is the name for the area w/entry points of the small perforating (ganglionic) aa?
Anterior and posterior perforated substance
What are the layers of the BBB?
- Endothelial cells w/tight junctions (large role)
1a. Endothelial basal lamina (proteins, carbs, lipids, etc.) - Pericytes (large role)
- Pia mater (in larger vessels only)
3a. Another Basal lamina - Astrocyte end-feet (likely smaller role)
- Neuronal processes (interact w/astrocytes and pericytes)
What are some roles of pericytes in the BBB?
- Form tight junctions of endothelial cells and regulate their vesicular trafficking
- Protect from immune response
- Can contract to allow different size cells through the vessels
(- They are likely crucial for post-natal formation of BBB)
Do cerebral vv. have valves?
Do they have anastomoses?
- No
- Yes, numerous
What is the fcn of emissary vv?
What’s a clinical implication of them?
Connect extracranial vv. w/dural venous sinuses
- Infection can spread from face/scalp into brain thru them
What are the 2 major divisions of the cerebral venous system?
Superficial + deep veins
Where does the superior group of superficial vv drain?
Superior and inferior sagittal sinuses
Where does the inferior group of superficial vv drain?
Transverse and cavernous sinuses
Where do vv. of the cerebellum and brainstem drain?
Deep sinus (great v. of Galen), straight sinus, transverse sinus, and petrosal sinus
Brain takes up __% of body weight, __%; CO, and __% O2 consumption
2, 15, 25
Normally, the brain uses __mL of blood/100g CNS/minute
At what level do neurons stop generating signals?
At what level does brain tissue necrosis begin to occur?
55
20mL
10mL
What cells control “autoregulation” of blood flow?
Arteriole and smooth m. cells
Explain the process of metabolic control of blood flow.
Increased neuronal activity → glutamate released → astrocyte end feet receptors activated → vasodilator factors released at end-feet applied to vessels
What are some of the main fcns of the BBB?
- Restrict ion/fluid movement
- Supplies essential nutrients
- Mediates efflux of waste or toxic products
What color are bones on CT? What about hemorrhages?
White, white
What are some drawbacks of MRI?
- Can’t do it w/metal (pacemakers…)
- Some people are claustrophobic
- Takes longer than CT (CT is for emergencies)
What is the source of bleeding for an epidural hematoma?
Middle meningeal a.
Define herniation syndrome, generally. Would it be more likely to occur in young or old people during a hemorrhage?
Parts of the brain expand so much that they push on other structures/brain stem
- Young, people their brain takes up more space in the cranial vault (old people already have atrophy)
Define Virchow-Robin space (perivascular space).
When bv’s come into neural tissue from the SAS they take some of the pia mater with them, and the space b/w the pia mater and the bv is called perivascular space.
What group of aa. comes off the basilar b/w AICA and SCA?
Pontine aa.
What a. comes off the ICA before it becomes the MCA and ACA?
Ophthalmic a.
What main a. comes off the middle cerebral a?
Anterior choroidal a.
