The pulmonary valve (sometimes referred to as the pulmonic valve) is a valve of the heart that lies between the

right ventricle A ventricle is one of two large chambers located toward the bottom of the heart that collect and expel blood towards the peripheral beds within the body and lungs. The blood pumped by a ventricle is supplied by an atrium (heart), atrium, an adjace ...

and the

pulmonary artery A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and ...

, and has three cusps. It is one of the four valves of the heart and one of the two

semilunar valves A heart valve is a biological Check valve, one-way valve that allows blood flow, blood to flow in one direction through the chambers of the heart. A mammalian heart usually has four valves. Together, the valves determine the direction of blood flow ...

, the other being the

aortic valve The aortic valve is a valve in the heart of humans and most other animals, located between the left ventricle and the aorta. It is one of the four valves of the heart and one of the two semilunar valves, the other being the pulmonary valve. ...

. Similar to the aortic valve, the pulmonary valve opens in ventricular systole when the pressure in the right ventricle rises above the pressure in the pulmonary artery. At the end of ventricular systole, when the pressure in the right ventricle falls rapidly, the pressure in the pulmonary artery closes the pulmonary valve. The closure of the pulmonary valve contributes to the P2 component of the

second heart sound Heart sounds are the noises generated by the beating heart and the resultant flow of blood through it. Specifically, the sounds reflect the turbulence created when the heart valves snap shut. In cardiac auscultation, an examiner may use a steth ...

(S2).

Structure

The pulmonary orifice lies nearly in the horizontal plane, and is situated at a superior level than the aortic orifice.

Cusps

File:Lunules of semilunar leaflets of pulmonary valve.png File:Anterior semilunar leaflet of pulmonary valve.png File:Right semilunar leaflet of pulmonary valve.png File:Left semilunar leaflet of pulmonary valve.png File:Commissures of semilunar leaflets of pulmonary valve.png File:Nodules of semilunar leaflets of pulmonary valve.png At the apex of the

infundibulum An infundibulum (Latin for ''funnel''; plural, ''infundibula'') is a funnel-shaped cavity or organ. Anatomy * Brain: the pituitary stalk, also known as the ''infundibulum'' and ''infundibular stalk'', is the connection between the hypothalamus an ...

, the pulmonary orifice is guarded by three semilunar cusps - two anterior and one posterior, with free edges projecting upward into the lumen of

pulmonary trunk A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and t ...

. The cusps are named according to their positions during foetal development: the anterior, the posterior, and the septal cusp. The free edge of each cusp presents a fibrous nodule of semilunar cusp at the centre with two lateral thin portions, the lunule of semilunar cusp. Each cusp forms pocket like dilatation called pulmonary sinus at the initial portion of pulmonary trunk.

Clinical significance

The right heart is a low-pressure system, so the P2 component of the second heart sound is usually softer than the A2 component of the second heart sound. However, it is physiologically normal in some young people to hear both components separated during

inhalation Inhalation (or inspiration) happens when air or other gases enter the lungs. Inhalation of air Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...

Additional images

File:Gray493.png, Interior of right side of heart. File:Gray1216.svg, Front of

thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

, showing surface relations of

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

lungs The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory syste ...

(purple),

pleura The pleurae (: pleura) are the two flattened closed sacs filled with pleural fluid, each ensheathing each lung and lining their surrounding tissues, locally appearing as two opposing layers of serous membrane separating the lungs from the med ...

(blue), and

heart The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...

(red outline).

Heart valves A heart valve is a biological one-way valve that allows blood to flow in one direction through the chambers of the heart. A mammalian heart usually has four valves. Together, the valves determine the direction of blood flow through the heart. Hea ...

are labeled with " B", " T", " A", and "P". File:Pulmonary artery.jpg, Pulmonary valves File:Slide4xxxx.JPG, Pulmonary valves

References

External links