Question

Choose the INCORRECT statement related to human heart valves.

• A. The right atrioventricular aperture is guarded by tricuspid valve.
• B. The opening of the postcaval into the right atrium is guarded by a Thebesian valve.
• C. Openings of pulmonary veins into the left atrium lack valves.
• D. The openings of the pulmonary artery and the aorta are guarded by three semilunar valves.

Hint:

The valve at the mouth of the postcaval vein is the Eustachian valve, while the Thebesian valve guards the coronary sinus.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
Valves of the heart keep blood flowing in one direction. Some openings have special valves, and some have none.

Step 2: Check the statements
The right atrioventricular opening has the tricuspid valve, so (A) is true.
Pulmonary veins open into the left atrium without valves, so (C) is true.
The pulmonary trunk and aorta each have three semilunar valves, so (D) is true.

Step 3: Find the incorrect one
At the opening of the postcaval (inferior vena cava) into the right atrium the valve is the Eustachian valve. The Thebesian valve is at the opening of the coronary sinus, so (B) is incorrect.

Final Answer:
The incorrect statement is the one naming the Thebesian valve at the postcaval opening. \[ \boxed{\text{(B) }\text{The opening of the postcaval into the right atrium is guarded by a Thebesian valve.}} \]