Bicuspid valve is found between left auricle and left ventricle. It lets blood flow from left atrium to left ventricle and prevents backflow of blood into the left atrium from the ventricle. The tricuspid valve found between right ventricle and right atrium prevents backflow of blood from right ventricle to right atrium. The thick muscular walls of left ventricle allow blood to be pumped throughout the body. The thin walls of atria allow blood to be pumped to lungs (shorter distance).