Embryology: heart development: 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 · Embryology: heart development

Sample item

A cyanotic newborn has an egg-on-string heart shadow on chest radiograph. Echocardiography shows the aorta arising from the right ventricle and the pulmonary trunk from the left ventricle. What is the embryological defect?

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

The answer and the reasoning

A. Failure of the aorticopulmonary septum to spiral

The aorticopulmonary septum normally follows a spiral course, so that the aorta connects to the left ventricle and the pulmonary trunk to the right. If it descends straight, the great arteries are transposed, giving two parallel circulations that need a shunt to survive.

Option by option

  • A. Failure of the aorticopulmonary septum to spiral (correct)

    Correct. A straight septum produces transposition of the great arteries.

  • B. Anterosuperior displacement of the infundibular septum

    Anterosuperior displacement of the infundibular septum causes tetralogy of Fallot.

  • C. Complete absence of the aorticopulmonary septum

    Complete absence of the septum causes persistent truncus arteriosus with a single outflow vessel.

  • D. Failure of the endocardial cushions to fuse

    Failure of the endocardial cushions to fuse causes an atrioventricular septal defect.

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.

More Anatomy questions

Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is A, Failure of the aorticopulmonary septum to spiral. The aorticopulmonary septum normally follows a spiral course, so that the aorta connects to the left ventricle and the pulmonary trunk to the right.

Why is "Anterosuperior displacement of the infundibular septum" not the answer?

Anterosuperior displacement of the infundibular septum causes tetralogy of Fallot.

Why is "Complete absence of the aorticopulmonary septum" not the answer?

Complete absence of the septum causes persistent truncus arteriosus with a single outflow vessel.

Why is "Failure of the endocardial cushions to fuse" not the answer?

Failure of the endocardial cushions to fuse causes an atrioventricular septal defect.

What concept does this question test?

It tests Embryology: heart development in Anatomy. If it descends straight, the great arteries are transposed, giving two parallel circulations that need a shunt to survive.

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 Embryology: heart development?

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.