Blood Supply Flashcards
Vascular System
Responsible for blood supply aka circulatory system.
Brain has tight regulatory control over delivery of O2 + glucose and removal of CO2
2 arterial territories responsible of blood supply to the brain
Anterior and posterior cerebral circulation (2 of each)
Circle of Willis
Provides overlapping/backup blood supply
- Anterior and posterior circulations (interconnected via bilateral posterior communicating arteries) are part of the circle of Willis
Circle of Willis is an example of
An anastomosis that protects the brain when part of the vascular supply is blocked
2 anterior cerebral arteries are connected by the __________.
Anterior communicating artery
2 posterior cerebral arteries are connected to the __________ by the ___________.
Internal carotid arteries by the posterior communicating arteries
3 main cerebral arteries:
- Middle cerebral artery
- Anterior cerebral artery
- Posterior cerebral artery
Anterior circulation includes:
- Middle cerebral artery
2. Anterior cerebral artery
Posterior circulation includes:
Posterior cerebral arteries
Middle cerebral artery
Has superior and inferior divisions of cortical branches.
Takes indirect course through lateral sulcus, along insular cortex, and over the inner opercular surface of the frontal, temporal, and parietal lobes.
Anterior cerebral artery
Courses within sagittal fissure and around rostral end of corpus Callosum
Posterior cerebral artery
Courses through lateral part of the brain
MCA supplies
Most of the lateral convexity of the cortex (except leg area of motor homunculus)
- deep structure get blood from branches of internal carotid artery and proximal positions of cerebral arteries
- gray matter of cerebral cortex and underlying white matter are supplied by branches of distal portions of cerebral arteries
ACA supplies:
The cortex and white matter of medial frontal and parietal loves, and the anterior corpus callosum. A strip of cortex wide in later surface.
PCA supplies
Occipital lobes and medial and inferior temporal lobes and posterior corpus callosum
MCA - contralateral hemiparesis and hemisensory loss
Involving the face and arm (precentral and postcentral gyri)
MCA - hemineglect (right hemisphere)
Unawareness of space and own body contralateral to lesion. Patients unaware or deny they’re handicap
Parietalneglect syndrome
Failure to recognize side of body contralateral to injury. May not bathe contralateral side of body or shave contralateral side of face. Deny own limbs. Objects in contralateral visual field ignored.
MCA - anosognosia
(Right hemisphere)
Unawareness of dramatic impairments like blindness or paralysis
MCA - aphasia
(Left hemisphere)
Brock’s aphasias
Wernicke’s aphasias
Brock’s aphasia
Difficulty producing speech. Can understand but not talk
Wernicke’s aphasia
Difficulty comprehending speech. Can’t understand but can talk fluently, however their speech doesn’t make any sense.
ACA - contralateral hemiparesis
Paralysis or weakness of one side of the body
ACA - hemisensory loss
Involving leg and foot (paracentral lobule)
ACA - frontal lobe
Personality changes
PCA - occipital lobe: hemianopsia
Loss of vision for one half of the visual field
PCA - occipital lobe: visual agnosia
Inability to recognize or interpret objects in the visual field
PCA - temporal lobes
Memory impairment
PCA - temporal lobes: prosopagnosia
Damage in occipital and temporal lobes
- unable to identify the facial characteristics, may not recognize the face at all (face blinding)
- aware that some visual stimulus is present
- can describe particular aspects without difficulty
- can discriminate subtle shape differences, recognize sex, age, and likability of faces
- identify people by non-facial cues such as voice, body shape, gait
Stroke
Death or dysfunction of brain tissue due to vascular disease
Occlusive
Closure of a blood vessel - atherosclerosis and thrombosis
Hemorrhagic
Bleeding from a vessel- hypertension and aneurysm
Intraparenchymal hemorrhage
Within the brain
Extraparenchymal hemorrhage
At the brain surface (subarachnoid)
Hematoma
Accumulation of blood that clots
Embolus
Material (blood clot, air, fat) carried from one point to lodge in another
Embolism
Embolus becomes lodged in artery and obstruct flow
Aneurysm
Balloon-like dwelling in wall of artery
Ischemia
Insufficiency of blood supply
Infarction
Neuronal death
Venous drainage of cerebral hemispheres
- Superficial veins drain into super sagittal sinus and cavernous sinus
- deep veins drain into great vein of Galen
- superior sagittal sinus drains into the 2 transverse sinuses which lead to the sigmoid sinus that connects to the jugular vein
