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The ventricles contained within the rhombencephalon become the fourth ventricle, and the ventricles contained within the mesencephalon become the aqueduct of Sylvius. Separating the anterior horns of the lateral ventricles is the septum pellucidum : a thin, triangular, vertical membrane which runs as a sheet from the corpus callosum down to the ...
During systole, the ventricles contract, pumping blood through the body. During diastole, the ventricles relax and fill with blood again. The left ventricle receives oxygenated blood from the left atrium via the mitral valve and pumps it through the aorta via the aortic valve, into the systemic circulation. The left ventricular muscle must ...
In the second phase of ventricular diastole, called late ventricular diastole, as the ventricular muscle relaxes, pressure on the blood within the ventricles drops even further. Eventually, it drops below the pressure in the atria. When this occurs, blood flows from the atria into the ventricles, pushing open the tricuspid and mitral valves.
Fourth ventricle location shown in red (E), pons (B); the floor of the ventricle is to the right, the roof to the left. The fourth ventricle has a roof at its upper (posterior) surface and a floor at its lower (anterior) surface, and side walls formed by the cerebellar peduncles (nerve bundles joining the structure on the posterior side of the ventricle to the structures on the anterior side).
Lateral ventricles and horns The lateral ventricles connected to the third ventricle by the interventricular foramina. Each lateral ventricle takes the form of an elongated curve, with an additional anterior-facing continuation emerging inferiorly from a point near the posterior end of the curve; the junction is known as the trigone of the lateral ventricle.
Diastole (at right) normally refers to atria and ventricles at relaxation and expansion together—while refilling with blood returning to the heart. Systole (left) typically refers to ventricular systole, during which the ventricles are pumping (or ejecting) blood out of the heart through the aorta and the pulmonary veins.
As the pressure rises within the cavities of the ventricles, the mitral and tricuspid valves are forced shut. As the pressure within the ventricles rises further, exceeding the pressure with the aorta and pulmonary arteries, the aortic and pulmonary valves open. Blood is ejected from the heart, causing the pressure within the ventricles to fall.
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