Anterior view of the left chamber of the heart showing the mitral and aortic valves with blood cells.

Valves of proximal part of femoral and great saphenous veins, anterior view. A. Structure of valves. The valve is usually composed of two cusps and permits blood flow toward the heart, but not in the reverse direction.

Transection view of heart showing chambers; lower arrow demonstrates blood flowing between cardiac ventricles through opening in the ventricular septum.

Anterior view of pericardial sac interior made visible upon removal of the heart. The severed ends of eight major blood vessels and the oblique pericardial sinus are the main anatomical landmarks.

Anterior view of transparent heart with blood flow indicators.