Heart - LO 7
7. Identify the unique structures of the left ventricle.
L. atrioventricular (mitral, bicupsid) valve
Composed of two valve cusps (anterior & posterior) which attach to the fibrous ring surrounding the right AV orifice
Cusps are drawn together before L. ventricular contraction, thus preventing the flow of blood from the L. atrium to the L. ventricle to direct the flow of blood through the pulmonary valve
Close during systole; open during diastole
Chordae tendineae: thin cords that attach to neighboring valve cusps from the papillary muscles
Papillary muscles: two muscles that attached to the ventricular wall
Anterior & posterior papillary muscles
Trabeculae carneae: numerous in the L. ventricle
The heart walls of the L. ventricle are significantly thicker than in the R. ventricle due to the higher arterial pressure associated with systemic circulation
Aortic vestibule: smooth-walled portion of the L. ventricle leading into the aortic orifice
Aortic orifice: at the orifice, there is a transition from ventricle to ascending aorta
Aortic (semilunar) valve
Has three, semilunar cusps (posterior, right, and left)
Close during diastole; open during systole
When blood is pumped through the L. ventricle into the ascending aorta, the cusps project into the trunk
When relaxation of the ventricle occurs, the cusps meet (‘snap close’) to prevent blood from returning to the ventricle
Aortic sinuses (of Valsalva): dilations of the ascending aorta just superior to the cusps of the aortic valve (there are also sinuses of the pulmonary trunk)
The right coronary a. (RCA) and the left coronary a. (LCA) originate in the upper portions of the R. and L. aortic sinuses, respectively