Cardiac valves

The four cardiac valves direct the flow of blood through the heart during the cardiac cycle.

Gross anatomy

The heart valves are located in the cardiac fibrous skeleton:

• two are atrioventricular (AV) valves: the right-sided tricuspid valve (TV) and left-sided mitral (bicuspid) valve (MV)
  • open during diastole to direct blood flow from the atria to the ventricles
  • close during systole to prevent regurgitation back into the atria from the ventricles
  • are attached to papillary muscles via chordae tendineae
• two are semilunar valves: the right-sided pulmonary valve (PV) and left-sided aortic valve (AV)
  • open during systole to direct blood flow from the contracting ventricles through the right ventricle and left ventricle outflow tracts to the pulmonary trunk and ascending aorta, respectively
  • close during diastole to prevent regurgitation back into the ventricles from the pulmonary trunk and ascending aorta
  • these valves do not have chordae tendineae or papillary muscles

It is best to list the four valves in the order which blood travels through the heart:

1. venous blood returning from the body drains into the right atrium via the SVC, IVC and coronary sinus
2. the right atrium pumps blood through the tricuspid valve into the right ventricle
3. the right ventricle pumps blood through the pulmonary semilunar valve into the pulmonary trunk to be oxygenated in the lungs
4. blood returning from the lungs via the pulmonary veins drain into the left atrium via the four pulmonary veins
5. the left atrium pumps blood through the bicuspid (mitral) valve into the left ventricle
6. the left ventricle pumps blood through the aortic semilunar valve into the ascending aorta to supply the body

See also

• prosthetic heart valves