Question

Cusps of ______ resemble half-moon shape?
(a) Tricuspid
(b) Semilunar valve
(c) Bicuspid valve
(d) Eustachian valve

Answer 1

Hint: The cusps that resemble a half-moon shape include the pulmonary valve and the aortic valve. The pulmonary valve guards the opening between the right ventricle and pulmonary artery whereas the aorta valve guards the opening between the left ventricle and aorta.

Complete Answer:
The cusps that resemble half-moon shapes are known as semilunar valves which are further of two types known as the pulmonary valve and the aortic valve. These valves are more similar to the valve found in the blood vessels of veins compared to atrioventricular valves.

The atrioventricular valves have chordae tendineae supporting them but the semilunar valves do not. Both the valves have three cusps in them. The closure of the semilunar valves results in the production of the second heart sound “dub” which can be heard using a stethoscope.

Additional information:
Tricuspid valve: It is a valve made up of three cusps and it guards the opening between the right atrium and right ventricle.
Bicuspid valve: It is a valve made up of two cusps and it guards the opening between the left atrium and left ventricle. It is also known as mitral valve as it looks similar to the bishop’s miter.
Eustachian valve: It is also known as the valve of the inferior vena cava and it guards the opening between the inferior vena cava and right atrium.
So, the correct option is ‘(b) Semilunar valve’.

Note:
- There are two heart sounds produced during the cardiac cycle “lub” and “dub” and they have clinical significance.
- The “lub” sound is produced by the closure of the tricuspid and bicuspid valves.
- The chordae tendineae are attached to the atrioventricular valves and prevent them from inverting inside.