Blood Supply to the Brain - Benifla Flashcards
What is the average weight of the brain?
What is the oxygen consumption?
1.2kg in women, 1.4 in men
15% of cardiac output
20% O2 consumption
What is the arterial input to the brain?
2 internal carotid arteries (sections: cervical, intrapetrosal, intracavernous, cerebral)
2 vertebral arteries
What are the branches of the internal carotid artery?
Meningohypophyseal tract (posterior hypophyseal lobe)
Ophthalmic
Superior hypophyseal (optic chiasm and anterior hypophyseal lobe)
Posterior communicating (PCom- caudomedial supply to Circle of Willis)
Anterior choroidal (choroid plexus of lateral ventricle, internal capsule, other parts of basal ganglia)
Anterior cerebral (ACA- connects left and right side of the internal carotid through anterior communicating artery, part of Circle of Willis)
Middle Cerebral (MCA-
What would injury to the right side of the anterior choroidal artery cause?
Left hemiparesis or hemiplegia
What are the branches of the Anterior Cerebral Artery (ACA)?
What does a tumor in this area (frontal lobe) cause?
Anterior communicating artery (connects right and left side)
Orbital artery (to orbital gyrus-inferior aspect of frontal lobe)
Frontopolar artery (below Genu to medial frontal lobe)
Terminates at Pericollosal artery (around corpus collosum- gives Collosomarginal artery to paracentral lobule and cingulate artery-provides leg and medial areas of homunculous and parietal lobes including precuneus)
Tumor would cause personality changes, paralysis of both legs, mimics spinal cord injury.
Rec. A. of Heubner (medial striate a )- Pass caudal and lateral enters the ant. Perforated sub. And supplies head of the caudate nucleus, putamen and internal capsule (not motor function). Medial part of hemisphere.
What are the branches of the middle cerebral artery (MCA)
Emerge from lateral sulcus over lateral convexity of hemisphere
Frontal (prefrontal and and lateral frontobasal-anterior part of superior and middle frontal gyrus)
Rolandic artery (central sulcus, pre and post central gyri)
Prerolandic (precentral sulcus and gyrus, inferior and middle frontal gyrus)
Posterior parietal- post central gyrus and superior parietal lobule
Angular A - supramarinal and angular gyruses
Pos. mid. and Ant. Temporal Arteries- superior and middle temporal gyruses (upper temporal lobe)
Parietal
Central arteries (lenticular striated arteries)
What is the effect of CVA in the middle cerebral artery?
Left hemiparalysis of the and and weakness of the leg
Since leg is in medial aspect of the homunculus, it is anastemosed with the ACA
The hand is more lateral so it only receives MCA blood
Hand is more impaired than leg
What is the main cause of hemineglect?
Isolated infarct of the angular artery (MCA branch) in the nondominant hemisphere
What is the effect of hypertension on the central arteries (lenticular striated arteries)
Small branches to deep brain (basal ganglia), supply lentiform nucleus and striatum
Emerge at 90’ from major cerebral artery. In HTN, blood that comes in high flow can’t make this turn and will injury to the wall of the artery. The wall of the articular striated arteries are damaged over time because flow damages wall.
Since wall is weakened, artery might explode. The basal ganglia is the most common location for CVA.
What arteries supply the posterior circulation of the brain?
Vertebral arteries- arise from the subclavian A and through the transverse foramen of C6-C1 (NOT C7) enters the foramen magnum into the posterior fossa along medulla oblongata.
Join to form basilar artery.
What are the branches of the vertebral arteries?
Posterior Spinal Artery - runs along spinal cord and supplies the posterior aspect
Posterior inferior cerebrellar artery (PICA) - along medulla supplying lower parts of cerebellum, inferior parts of vermis tonsils and part of choroid plexus of fourth ventricle
What are the branches of the Basilar artery?
Anterior inferior cerebellar artery (AICA)- supplies the caudal parts of the pons and tegmentum (medial aspects of brainstem and inferior cerebellum), inferior surface of cerebellar hemisphere- DOES NOT SUPPLY MEDIAL CEREBELLUM
Short and long pontine arteries - brainstem
Labyrinthine artery - long, along internal auditory meatus and inner ear, parts of cerebellum
Superior cerebellar A - superior surface of cerebellum and cerebella nuclei
Postterior cerebral artery - from bifurcation of basilar artery, laterally around crus cerebri, anastomoses with PCom (connects to anterior circulation) and continues to lateral aspect of midbrain, above tentorium on medial and inferior surfaces of temporal and occipital lobes (calcarine and lingual gyri), brain stem, third and lateral ventricle choroid plexi (through posterior choroid artery), cerebral cortex.
- Infarct causes contralateral homonymous heminopsia
- Bilateral damage: cortical blindness
Circle of Willis
Arterial wreath encircling the optic chiasm, the tuber cinereum
Communication between anterior and posteior circulation and left and right
Formed by anastemoses between branches of the ICA and Basilar A (so blockage will be compensated)
ACA-ACOM-ACA-(internal carotid)-PCOM-PCA-PCA-PCOM-(internal carotid)-ACA
Closing the MCA will cause blockage of its branches laterally
Anteromedial arteries are central arteries on the anterior side
Posteromedial arteries are central arteries on the posterior side
What are the superior and inferior anastamoses of the venous sinuses?
Superior anastamotic - Trolard
Connects the superior saggital vein and the superficial middle cerebral vein (of Sylvius).
Inferior anastamotic- Labbe
Connects the middle cerebral vein and the transverse sinus.
Maintains venous drainage even when one is closed. Infarct causes increased pressure and edema (fatal).
Deep brain venous drainage
Where do they go?
Basal vein of Rosenthal
Formed by anterior cerebral and deep middle cerebral veins
Come around brainstem and drain part of brainstem
Drain into great vein of Galen which drains into rectus sinus (confluence, sigmoid, IJV)
Thalamostriate vein
From thalamus and striatum (part of basal ganglia)
Unites with interior septal vein to form the (2) internal cerebral vein (runs along midline of interior side of third ventricle)
Drain into great vein of galen
Central veins drain brainstem and cerebellum
