The right ~ventricle~ is a large lower cavity of the |heart|. The walls of the ~ventricle~ are a quarter of an inch thick and are composed of three spiraling layers of muscle: the superficial layer, the deep sinospiral layer, and the bulbo spiral layer. All three bands of muscle anchor firmly onto the skeleton of the |heart|.Toward the top of the chamber, near the |pulmonary artery|, the inner surface is smooth. Throughout the rest of the chamber, small bundles of muscle arise from the walls, stretch and then merge with other bundles. They weave an intricate web of tissue across the ~ventricle~. When the right ~ventricle~ contracts, ~blood~ rushes into the |pulmonary artery| and into the |lungs|. The right ~ventricle~ holds slightly more than a quarter of a cup of ~blood~.
