atrioventricular orifice (left heart, anatomy)
Last reviewed 01/2018
The atrioventricular orifice of the left heart is the roughly circular aperture between the left atrium and the left ventricle that is surrounded by the mitral valve. When fully open, typically its circumference is about 8cm in the adult; it is smaller than the tricuspid orifice.
The plane of the orifice is anteriorly, inferiorly and to the left - a line through its centre would intersect at or near to the apex of the left ventricle.