Anatomical studies on the atrioventricular valves of the ostrich heart (Struthio camelus)

Ostrich hearts of both sexes and aged 9-12 month were studied grossly by sagittal and transverse sections.The right atrioventricular orifice of ostrich heart was guarded by a single triangular muscular plate which acted with the bulged convex interventricular septum as the right atrioventricular valve.This plate was fixed to the parietal wall of the right ventricle by a muscular bundle and to the right side of interventricular septum by a membrane.There was a sac between the right ventricular parietal wall and the outer surface of the triangular muscular plate formed between the most cranial thick border of the right atrioventricular valve and the basal wall of the right ventricle.The left atrioventricular orifice was guarded by three cusps; septal, left cranioparietal and right caudoparietal.The septal cusp was somewhat triangular in outline while the left and right cranioparietal cusps were somewhat quadrilateral in shape.The left ventricle has three small papillary muscles and chordae tendinae which were classified into true and false chordae tendinae according to their point of insertion.The longitudinal trabeculae carneae were rosette-like shaped in cross-sections and increased in number toward the apex.