neuro lec 5 Flashcards
Diff bw arterial vs venous system?
- Arterial: supplies oxygenated blood to brain, includes arteries, arterioles, capillaries.
- Venous: removes deoxygenated blood from brain back to heart/lungs, includes venules, veins, sinuses.
Why do brain cells require constant oxygen and glucose?
Because brain does not store these things
Diff bw systolic vs diastolic pressure?
- Systolic = away from heart
- Diastolic = passive return of blood towards heart
What are the parts of the internal carotid system? (2)
- Anterior cerebral arteries
- Middle cerebral arteries
What are the parts of the vertebrobasilar system? (2)
- cerebellar arteries (several)
- Right and left vertebral arteries form the basilar artery at the level of the pons
What is the circle of Willis?
- Where the basilar artery joins the internal carotid system at the base of the brain
- Allows for collateral circulation (alternative routes in case of blockage)
Whats the connection bw vertebral arteries and posterior cerebral arteries?
Vertebral arteries go into the skull from the neck and join together into the basilar artery which then joins the circle of willis and turns into the posterior cerebral arteries
Whats the connection bw the internal carotid and the anterior/middle cerebral arteries?
Internal carotid go into the skull from the front of the neck and joins the circle of willis becoming the anterior/middle cerebral arteries
What kind of blood do superior cerebral veins receive? Where do they drain into (3)?
- Deoxygenated blood from cortical surfaces
- Drain into superior and inferior sagittal sinus, straight sinus, and transverse sinus
What do deep cerebral veins drain? Where do they converge?
- Drain deep structures of brain
- Converge on internal cerebral veins – inferior sagittal sinus above 3rd ventricle, continue into straight and sigmoid sinuses
Superior and deep cerebral veins join at the confluence of sinuses and empty into the internal ____.
Jugular veins
Which sinus receives blood from the frontal, parietal, and occipital veins?
Superior sagittal sinus
Which sinus drains the medial aspects of the frontal lobe and cingulate gyri?
Inferior sagittal sinus
Which sinus is posterior and superior to the cerebellum?
Straight sinus
Which sinus is lateral to the cerebellum and runs in the grooves of the occipital bone and squamous temporal bone?
Transverse sinus
The great cerebral vein continues into the ____ sinus, which then drains into the ____ sinus.
- Straight
- Sigmoid
Function of blood brain barrier (BBB)? (2)
- Protects brain against toxic substances and allows essential nutrients in
- Protect against abnormal variations in concentration of ions and molecules
What are the 3 cortical arteries? Which one is largest?
- Anterior cerebral artery
- Middle cerebral artery (largest)
- Posterior cerebral artery
Where does the anterior cerebral artery start/stop? What does it do?
- Emerges through lateral fissure onto lateral surface of brain
- Supplies sensory and motor cortices to arms, hands, and face…
Where is the posterior cerebral artery? What does it do?
- Splits from basilar artery to go laterally to inferior temporal lobe and caudally occipital lobe
- Supplies occipital lobe and inferior temporal lobe, thalamus, midbrain (visual processing, relay station)
What is a cerebrovascular accident?
Stroke – brain cells die b/c deprived of oxygen and glucose
What is an occlusive/ischemic stroke? How common are they?
- When something plugs/blocks the artery to prevent blood flow
- 80-90% of all strokes
What is atherosclerosis? What type of stroke does it fall under?
- hardening of artery walls as junk/fat build up (leads to thrombosis or embolism)
- Occlusive stroke
What is a transient ischemic attack? What type of stroke does it fall under?
- temporary interruption of blood flow for a few minutes to an hour
- Occlusive stroke
What is thrombosis? What type of stroke does it fall under?
- complete blockage of blood vessel (most common)
- Occlusive stroke
What is embolism? What type of stroke does it fall under?
- chunk of undissolved substance narrows or plugs a blood vessel
- Occlusive stroke
What is a hemorrhagic stroke?
- bleeding or rupture of blood vessels under pressure
What is an extracerebral vs intracerebral hemorrhage?
- Extra = within meninges
- Intra = within cortex
What are the 3 types of extracerebral hemorrhages?
- Epidural: under skull
- Subdural: under dura mater
- Subarachnoid: under arachnoid mater
What is an aneurism? Is this considered extra or intracerebral?
- Balloon in weakened artery wall which may rupture
- Intracerebral
What is one risk factor for hemorrhagic strokes?
High blood pressure
What is an arteriovenous malformation? Is it common?
- Present at birth – tangles which may cause seizures/headaches/hemorrhage
- Rare
Diff bw embolism vs thrombosis vs atherosclerosis?
- Embolism = floating clots
- Thrombosis = full blockage
- Atherosclerosis = partial blockage
functions of meninges? (5)
- Protect the brain
- Maintain brain in fluid suspension/cushion
- Hold structures in place during movement
- Provide nutrients (CSF)
- Passageway for blood vessels (arachnoid mater)
what are the 4 layers of the meninges?
- skull
- dura mater (tough)
- arachnoid mater (spider)
- pia mater (tender)
which layer of meninges makes direct contact w brain’s surface?
pia mater
which layer of meninges forms sinuses for venous blood drainage?
dura mater
where is the epidural space?
between the outer layer of the dura mater and the inner surface of the skull or vertebral canal
where is the subdural space?
between the dura mater and the arachnoid mater
where is the subarachnoid space?
between the arachnoid mater and the pia mater
where is CSF located?
subarachnoid space + circulates around the brain and spinal cord
what is a hematoma?
abnormal collection of blood
function of ventricles? how many do we have in our brains?
- circulate CSF
- 4
the ventricle system is interconnected to the ____ space thru ____ in the ____ ventricle
- subarachnoid
- foramen
- 4th
what are the 2 paired lateral ventricles connected by?
interventricular foramen
where is the 3rd ventricle?
diencephalon
where is the 4th ventricle?
dorsal pons and medulla
what are the 3rd and 4th ventricles connected by?
cerebral aqueduct
what is the CSF produced by?
choroid plexus (present in each ventricle)
where does CSF drain? how much of it is produced daily?
- into the venous system of the blood supply
- 500ml a day
parts of lateral ventricle? (3)
- anterior horn
- posterior horn
- inferior horn
CSF absorbs __% of the brain’s weight
95
T or F: CSF gets reabsorbed
true – reabsorbed by arachnoid granulations that dump into sagittal sinus
what is hydrocephalus?
- increased fluid and decreased drainage/reabsorption in head
- results in enlarged ventricles and enlarged cranium, esp in children since fontanelles
