Blood Supply Flashcards
Why does the brain have very dense vasculature?
critical for optimal functioning
highly sensitive to O2 disturbances
What are the anterior and posterior arteries?
anterior: internal carotid artery, external carotid artery, common carotid artery
posterior: basilar artery, vertebral artery
What do the anterior and posterior circulation supply?
each hemisphere
What is neuroangiography?
image vasculature by inserting a catheter into the femoral artery and feeding it up, then injecting a contrast agent
What is the function of an anastomosis? (circle of Willis)
protects the brain when part of the vasculature is blocked
What arteries are involved in the circle of Willis?
internal carotid arteries (pre bifurcation)
middle cerebral arteries (proximal)
anterior cerebral arteries (proximal)
anterior communicating artery (single artery)
posterior communicating artery (connects circle)
posterior cerebral arteries (proximal)
basilar artery (single artery)
What are the most common sites of intracranial saccular aneurysm?
30% - anterior communicating artery
25% - posterior communicating arteries
20% - middle cerebral arteries
What are the main cerebral arteries?
middle cerebral artery
anterior cerebral artery
main cerebral artery
Where does the MCA supply?
superior and inferior divisions of cortical branches
takes and indirect course through the lateral sulcus, along the insular cortex, and over the inner opercular surface of the frontal, temporal, and parietal lobes
Where does the ACA supply?
course within the sagittal fissure and around the rostral (front) end of the corpus callosum
Where does the PCA supply?
the course around the lateral part of the midbrain
What are the cortical areas the MCA supplies?
most of the lateral convexity and white matter (except leg area of motor homunculus), including frontal, parietal, temporal, occipital lobes and insula
What are the cortical areas the ACA supplies?
cortex and white matter of medial frontal and parietal lobes, anterior corpus callosum, a strop of the cortex (he 1 in wide) on t lateral surface
What are the cortical areas the PCA supplies?
occipital lobes and portions of medial and inferior temporal lobes, posterior corpus callosum
How do deep structures of the brain receive blood?
directly from the branches of the internal carotid artery and proximal portions of the cerebral arteries
What arteries supply the grey matter of the cerebral cortex and underlying white matter?
branches of more distal portions of the cerebral arteries
What is the most common site for vascular syndromes?
MCA
What vascular syndromes are associated with the MCA?
contralateral hemiparesis and hemisensory loss involving mainly the face and arm (precentral and postcentral gyro)
What vascular syndromes are associated with the MCA (right hemisphere)?
hemineglect - unawareness of space and the patient’s own body contralateral to the lesion; patients may seem unaware or deny their handicap (anosognosia)
- failure to recognize the side of the body contralateral to injury, may not bathe or shove contralateral side of the face, deny won limbs, object in contralateral visual field ignored
What vascular syndromes are associated with the MCA (left hemisphere)?
aphasia - inability to comprehend or formulate language
What is Broca’s aphasia?
difficulty producing speech
What is Wernicke’s aphasia?
difficulty comprehending speech
What vascular syndromes are associated with the ACA?
contralateral hemiparesis - paralysis or weakness of one side of the body and hemisensory loss involving mainly leg/foot (paracentral lobe)
personality changes (frontal lobe)
What vascular syndromes are associated with the PCA?
occipital - hemianopsia - loss of vision for one have of the visual field (typically contralateral homonymous hemiopsia)
- visual agnosia - inability to recognize or interpret object in the visual field
temporal - memory impairment
What is prosopagnosia?
damage to the inferior temporal cortex (most common PCA stroke)
- unable to identify facial characteristics or faces at all
- aware some sort of visual stimulus is present
- can describe particular aspects without difficulty
- can discriminate subtle shape differences
- recognize the sex, age, and ‘likeability’ of faces
- identify people by non-facial cues (voice, body shape, gait)
Define stroke
death or dysfunction of brain tissue due to vascular disease
Define infarction
neuronal death
Define ischemia
insufficiency of oxygen supply
Define anoxia
reduced oxygen supply
Define embolus
material (blood clot, air, fat) carried from one point to lodge in another
Define embolism
embolus becomes lodged in an artery and obstructs flow
Define hemorrhagic
bleeding (rupture) from a vessel (hypertension and aneurysm)
Define occlusive
closure (blockage) of a vessel (atherosclerosis and thrombosis)
What is tissue plasminogen activator used for?
a protease enzyme that catalyzes the conversion of plasminogen to plasmin, the major enzyme responsible for clot breakdown
Define intraparenchymal hemorrhage
within the brain
Define extraparenchymal hemorrhage
at the brain surface (subarachnoid)
Define intracranial aneurysm
weakness in the wall of a cerebral vasculature causes a localized dilation or ballooning of the blood vessel
How are intracranial aneurysms treated?
endovascular coiling - aneurysm is filled with a coil to prevent further growth and rupture
surgical clipping
Where do superficial veins drain?
into the superior sagittal sinus and cavernous sinus
Where do deep veins drain?
into the great vein of Galen
Where does the superior sagittal sinus drain?
into the two transverse sinuses, which leads to the sigmoid sinus that connect to the jugular vein
