Heart walls of the heart to valves by cartilaginous connections called chordae tendinae. These muscles prevent the valves from falling too far back when they close. During the relaxation phase of the cardiac cycle, the papillary muscles are also relaxed and the tension on the chordae tendineae is slight. As the heart chambers contract, so do the papillary muscles. This creates tension on the chordae tendineae, helping to hold the cusps of the atrioventricular valves in place and preventing them from being blown back into the atria. Two additional semilunar valves sit at the exit of each of the ventricles. The
Lateral ventricles flat, the lateral ventricles have a vaguely triangular cross-section. Ependyma, which are epithelial cells, cover the inside of the lateral ventricles. The anterior horn of lateral ventricle or "frontal horn", is the portion which connects to the 3rd ventricle, via the interventricular foramen. This portion of the lateral ventricle impinges on the frontal lobe, passing anteriorly and laterally, with slight inclination inferiorly. It is separated from the anterior horn of the other lateral ventricle by a thin neural sheet - septum pellucidum, which thus forms its medial boundary. The boundary facing exterior to the ventricle curvature is formed by the