Thorax: Eustachian valve in the fetal heart: practice question

A Anatomy question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Anatomy · Thorax: Eustachian valve in the fetal heart

Sample item

In the fetal right atrium, a crescentic fold at the lower margin of the caval opening helps to direct oxygen-rich blood across the foramen ovale. What is this fold called?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Eustachian valve

The Eustachian valve is the remnant of the right valve of the sinus venosus at the inferior vena caval orifice, and in fetal life it steers blood towards the foramen ovale. The Thebesian valve guards the coronary sinus orifice. In the adult it is small or absent.

Option by option

  • A. Thebesian valve

    The Thebesian valve guards the opening of the coronary sinus, not the caval orifice.

  • B. Limbus fossae ovalis

    The limbus is the rim of the fossa ovalis on the interatrial septum, not a valve at the caval opening.

  • C. Eustachian valve (correct)

    Correct. It lies at the lower caval orifice and directs blood to the foramen ovale.

  • D. Crista terminalis

    The crista terminalis is the muscular ridge separating the smooth and trabeculated parts of the right atrium.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is C, Eustachian valve. The Eustachian valve is the remnant of the right valve of the sinus venosus at the inferior vena caval orifice, and in fetal life it steers blood towards the foramen ovale.

Why is "Thebesian valve" not the answer?

The Thebesian valve guards the opening of the coronary sinus, not the caval orifice.

Why is "Limbus fossae ovalis" not the answer?

The limbus is the rim of the fossa ovalis on the interatrial septum, not a valve at the caval opening.

Why is "Crista terminalis" not the answer?

The crista terminalis is the muscular ridge separating the smooth and trabeculated parts of the right atrium.

What concept does this question test?

It tests Thorax: Eustachian valve in the fetal heart in Anatomy. The Thebesian valve guards the coronary sinus orifice. In the adult it is small or absent.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Thorax: Eustachian valve in the fetal heart?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.