Heart of the 18-mm embryo. (A-V, atrioventricular.)
Keywords: apex, arch of aorta, ascending aorta, atrioventricular sulcus, axillary artery, brachiocephalic artery, ductus arteriosus, inferior vena cava, interventricular sulcus, left atrium, left common carotid artery, left subclavian artery, left ventricle, pulmonary trunk, right atrium, right common carotid artery, right subclavian artery, right ventricle, superior vena cava, thyrocervical trunk, vertebral artery
Source: Atlas of Human Embryos.