The left atrioventricular opening (mitral orifice) is placed below and to the left of the aortic orifice.
It is a little smaller than the corresponding aperture of the opposite side.
It is surrounded by a dense fibrous ring, covered by the lining membrane of the heart, and is guarded by the bicuspid or mitral valve.
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|Anatomy of torso, cardiovascular system: heart|
|Structures||atria (interatrial septum, musculi pectinati) • ventricles (interventricular septum, trabeculae carneae, chordae tendinae, papillary muscle) • valves • cusps|
|Regions||base • apex • grooves (coronary/atrioventricular, interatrial, anterior interventricula, posterior interventricular) • surfaces (sternocostal, diaphragmatic) • borders (right, left)|
|Right heart||(vena cavae, coronary sinus) → right atrium (auricle, fossa ovalis, limbus of fossa ovalis, crista terminalis, valve of the inferior vena cava, valve of the coronary sinus) → tricuspid valve → right ventricle (conus arteriosus, moderator band/septomarginal trabecula) → pulmonary valve → (pulmonary artery and pulmonary circulation)|
|Left heart||(pulmonary veins) → left atrium (auricle) → mitral valve → left ventricle → aortic valve (aortic sinus) → (aorta and systemic circulation)|
|Layers||pericardium: fibrous pericardium • serous pericardium (pericardial cavity, epicardium/visceral layer) • pericardial sinus|
myocardium • endocardium • cardiac skeleton (fibrous trigone, fibrous rings)
|Conduction system||Cardiac pacemaker • SA node • AV node• bundle of His • Purkinje fibers|