International Journal of Health Sciences & Research (www.ijhsr.org) 253 Vol.4; Issue: 11; November 2014 International Journal of Health Sciences and Research www.ijhsr.org ISSN: 2249-9571 Case Report Tetracuspid Right Atrioventricular Valve: A Case Report Vrinda Hari Ankolekar 1 , Aswin Das 2 , Anne D Souza 1 , Antony Sylvan D Souza 3 , Mamatha Hosapatna 4 1 Assistant Professor, 2 Postgrduate Student, 3 Professor and Head, 4 Associate Professor; Department of Anatomy, Kasturba Medical College, Manipal University, Manipal. Karnataka, India, Pin: 576104 Corresponding Author: Mamatha Hosapatna Received: 11/09//2014 Revised: 11/10/2014 Accepted: 11/10/2014 ABSTRACT The right atrioventricular valve (tricuspid valve) allows blood to flow from the right atrium down into the right ventricle. Tricuspid valve disease is rare, but includes tricuspid valve regurgitation, stenosis, and Ebstein anomaly. During regular dissections for undergraduate medical students, in the department of Anatomy, Kasturba Medical College, Manipal, we observed the following variations in the heart in an adult male cadaver. The right atrioventricular valve showed four cusps instead of usual three cusps, anterior, posterior, septal. The extra cusp was anterolateral in position. This variation is important for the cardiothoracic surgeon. Key words: Tricuspid valve, conus arteriosus, chordae tendineae, septal cusps, papillary muscle INTRODUCTION The right atrioventricular valve (tricuspid valve) allows blood to flow from the right atrium down into the right ventricle. Tricuspid valve disease is rare, but includes tricuspid valve regurgitation, stenosis, and Ebstein anomaly. The right AV valve has three, roughly triangular shaped, cusps that project into the ventricle: the anterior (superior), posterior (inferior) and septal. The anterior is the largest cusp interposed between the AV orifice and the conus arteriosus. The posterior is connected to the right margin of the ventricle and the septal cusp to the ventricular septum. The bases of the cusps are attached to a fibrous ring at the AV orifice, where they are continuous with one another. The ventricular surfaces of the cusps are divided into three zones: the distal rough zone, the basal zone and the proximal, thin and translucent clear zone. (1) The rough zone serves as points of insertion for the chordae tendineae, which arise from the apices of conical muscular projections of the ventricle wall, called papillary muscle. (2) CASE REPORT During regular dissections for undergraduate medical students, in the department of Anatomy, Kasturba Medical College, Manipal, we observed the following variations in the heart in an adult male cadaver. The right atrioventricular valve showed four cusps instead of usual three cusps, anterior, posterior, septal. The extra cusp was anterolateral in position as shown in figure 1.