|Left atrioventricular opening
||ostium atrioventriculare sinistrum
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.
This article incorporates text from a public domain edition of Gray's Anatomy.