The interventricular septum occupies the anterior and right-hand wall of the left ventricle. The thickest portion of this chamber is called the pars muscularis, and the thinnest portion the pars membranecea. The mitral or bicuspid valve prevents the backflow of blood from the left ventricle to the left atrium. Since there are two cusps there are also two papillary muscles located in the left ventricle. The chordae tendinae of each go to both of the cusps of the mitral valve.
Blood leaves the left ventricle via the aortic valve .
This valve is very similar to the pulmonary valve. Each aortic cusp will house a sinus. The sinuses are matched with their respective cusp. From the right and left sinus originates the right and left coronary arteries. The posterior sinus and valve are designated as the noncornary sinus and cusp.