Blood Supply Flashcards
What are the four main blood vessels for the brain?
Right/Left Vertebral and Right/Left Internal Carotid Arteries
What is anterior vs posterior circulation in the brain? What parts of the brain do they supply with blood?
Anterior: Internal carotid and forward; Supplies cerebrum
Posterior: Posterior Cerebral Artery and backwards; Supplies mostly cerebellum and brainstem (one exception)
What is another name for posterior circulation?
Vertebrobasilar System
What arteries are in the posterior circulation?
- Vertebral
- Anterior Spinal
- Posterior Inferior Cerebellar
- Anterior Inferior Cerebellar
- Basilar
- Pontine
- Superior Cerebellar
- Posterior Cerebral
Anterior spinal artery is formed by ____
What does it supply?
- Vertebral arteries enter cranial cavity uniting to form the artery
- Send blood supply to the spinal cord and some portions of the medulla
What do the posterior inferior cerebellar arteries supply?
Cerebellum and portions of the medulla
What arteries create the basilar artery?
Where does the artery run in the brain?
- Vertebral come together to form one basilar artery
- Runs along the clivus of the occiput
Where do the pontine arteries come from?
What do they supply?
- Come from basilar artery
- Supply the brainstem
What does the anterior inferior cerebrella arteries supply? What would a blockage here cause?
- The cerebellum
- Issues with coordination, motor learning and postural control
What does the Labyrinthine Artery supply? Where is it located? If a blockage occured here what deficits would we see?
- Supplies the ear with branches going to the cochlear and to the semicircular canals
- Located in the ear and branch of either basilar artery or anterior inferior cerebellar artery
- Blockage would result in hearing loss or vestibular damage
What does the superior cerebellar artery supply? Where does it come from?
- Cerebellum and parts of the midbrain
- Comes off the basilar artery
What seperates the posterior cerebral artery and superior cerebellar artery?
Tentorum Cerebelli
What is so special about the posterior cerebral artery?
It is in the posterior circulation but supplies the occipital lobe and adjacent portions of the temporal, parietal and limbic lobes.
A blockage to the posterior cerebral artery would result in what?
Visual problems, sensory association issues and behavioral changes
What arteries comes of the posterior cerebral artery? What does it supply?
- Thalamoperforate Arteries
- Supply the thalamus
A block of the thalamoperforate arteries would result in what?
- Major sensory loss, all sensory information goes through the thalamus
What is more dangerous, a blockage to the posterior circulation or anterior circulation and why?
Posterior as it supplies things such as the midbrain, pons and medulla that help with functions to survive. Posterior result in coordination deficits or fatal outcomes.
What are some common signs and symptoms of posterior circulation deficits?
- Dizziness or vertigo
- Dysarthria (inability to use speaking muscles/can’t speak)
- Nausea or vomiting
- Loss or alteration of conciousness
- Limb weakness
- Ataxia
- Nystagmus (lac of control of horiztonal gaze; eye sovershoot)
Where do the internal carotid arteries enter the cranial cavity?
Through the carotid canals of the temporal bone
Internal carotid arteries give off what interesting artery? What does it supply?
- Opthalamic A.
- Supplys the contents of the orbit
What arteries make up the anterior circulation?
- Internal Carotid
- Middle Cerebral
- Anterior Cerebral
- Anterior Communicating
Where does the anterior cerebral artery travel and what does it supply?
- Travels internally and anteriorly through the longitudional fissure
- Supplies anterior and superior aspects of the ftonal and parietal lobes and the interansl aspects of the ftonal, parietal and limbic lobes
What would a blockage of the anterior cerebral artery do?
Issues with decision making, motor movement of the legs, sensory association, behavior changes
Where is the anterior communicating A located?
- Lies next to the optic chiasm
- Not everyone has one
The earlier a blockage, results in?
Wider spread effects
Where does the middle cerebral A come from? Where does it go and what does it supply?
- Comes off the internal carotid
- Moves laterally/external to supply the frontal, parietal and temporal lobes
What artery comes off the middle cerebral and what does it supply?
- Lenticulostriate A.
- Supply the basal ganglia and large portions of the internal capsule
A blockage of the lenticulostriate arteries would result in what?
Massive sensory and motor loss as both travel throgh the internal capsule
The middle cerebral artery may also give off what artery?
- Posterior communicating arteries; Anastomoses with the posterior cerebral arteries
- NOT ALWAYS PRESENT
Ring of Cerebral anastomoses is called
Circle of Willis
Anterior circulation pathology often results in what?
- Functional deficits
- Sometimes death when severe
What is the blood brain barrier?
- Passage that restricts large molecules from the bloodstream
- Blood/Cerebrospinal Fluid Barrier
– Chorioid plexuses (of ventricles) filtrate CSF from blood
– Only clear plasma passes through leaving blood cells behind
– Formed by the fusion of the pia mater and the ependyma (ventricular lining) - Arachnoid Barrier
– Formed by tight junctions between endothelial cells of cerebral capillaries in the arachnoid mater
– Certain molecules can pass, while some larger are prevented.
Clincial importance of the arachnoid barrier
In pharmacuticals will give the precursor substance (Ex: L-DOPA) which is small enough to pass through and then the brain does the rest to convert it where it is needed (Ex: dopamine)
Venous Drainage
- Not as common for problems
- No valves, blood can go bidirectionally
- Superficial and deep veins
- Superficial veins lie within the subarachnoid space largely repsonsible for draining cortex
- All blood drains into the straight sinus
Why is a subarachnoid bleed so dangerous? Who is most prone to getting one?
- Often don’t present with symptoms until late.
- As we age the brain starts to shrink and veins get more fragile with age, puts that more susceptible to a bleed. Another reason while falling in old age is a major risk.
