ckest part of the wall is at the base and it gradually becomes thinner towards the apex. The cavity can contain up to two ounces of fluid. There are two openings in the right ventricle; the auriculo-ventricular opening and the opening of the pulmonary artery. The auriculo-ventricular opening is the large oval opening between the right atrium and the right ventricle. The opening is about an inch in diameter. It is surrounded by a fibrous ring, covered by the lining membrane of the heart (endocardium), and is larger than the opening between the left atrium and the left ventricle. It is protected by the tricuspid valve. The opening of the pulmonary artery is round and is situated at the top of the conus arteriosus, close to the septum. It is on the left side and is in front of the auriculo-ventricular opening. It is protected by the semilunar valves.3 There are two main valves associated with the right ventricle; the tricuspid valve and the semilunar valves. The tricuspid valve consists of three segments of a triangular shape, formed by the lining membrane of the heart (endocardium). They are strengthened by a layer of fibrous tissue and muscular fibers.1 These segments are connected by their bases to the auriculo-ventricular orifice, and by their sides with one another, so as to form a continuous membrane which is attached around the margin of the auriculo-ventricular opening. Their free margin and ventricular surfaces are attached to many delicate tendinous cords called chordae tendinae. The central part of each valve segment is thick and strong while the lateral margins are thin and indented. The chordae tendinae are connected with the adjacent margins of the main segment of the valves. The semilunar valves guard the opening of the pulmonary artery. They consist of three semicircular folds formed by the endothelial lining of the heart and are strengthened by fibrous tissue. They are attached by their c...
