Embryology: aortic arch anomalies: 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.

Try it

Anatomy · Embryology: aortic arch anomalies

Sample item

A 40-year-old woman has mild dysphagia. Barium swallow shows an oblique posterior indentation of the oesophagus, and angiography shows the right subclavian artery arising from the descending aorta and passing behind the oesophagus. Which embryological event explains this?

AFailed involution of the left dorsal aortaBAbnormal division of the truncus arteriosusCLoss of right fourth arch and proximal right dorsal aortaDPersistent double aortic arch from both fourth arches

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

The answer and the reasoning

C. Loss of right fourth arch and proximal right dorsal aorta

In an aberrant right subclavian artery, the right fourth arch and the right dorsal aorta above the seventh intersegmental artery disappear. The right subclavian then forms from the distal right dorsal aorta and seventh intersegmental artery and arises from the left side, crossing behind the oesophagus.

Option by option

A. Failed involution of the left dorsal aorta
Failed involution of the left dorsal aorta would not displace the right subclavian origin.
B. Abnormal division of the truncus arteriosus
Truncus arteriosus division defects cause outflow tract anomalies such as transposition.
C. Loss of right fourth arch and proximal right dorsal aorta (correct)
Correct. Loss of the right fourth arch and proximal dorsal aorta moves the origin of the right subclavian artery to the descending aorta.
D. Persistent double aortic arch from both fourth arches
A double aortic arch forms a vascular ring but both subclavian arteries arise normally from their own arches.

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.

Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is C, Loss of right fourth arch and proximal right dorsal aorta. In an aberrant right subclavian artery, the right fourth arch and the right dorsal aorta above the seventh intersegmental artery disappear.

Why is "Failed involution of the left dorsal aorta" not the answer?

Failed involution of the left dorsal aorta would not displace the right subclavian origin.

Why is "Abnormal division of the truncus arteriosus" not the answer?

Truncus arteriosus division defects cause outflow tract anomalies such as transposition.

Why is "Persistent double aortic arch from both fourth arches" not the answer?

A double aortic arch forms a vascular ring but both subclavian arteries arise normally from their own arches.

What concept does this question test?

It tests Embryology: aortic arch anomalies in Anatomy. The right subclavian then forms from the distal right dorsal aorta and seventh intersegmental artery and arises from the left side, crossing behind the oesophagus.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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: aortic arch anomalies?

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.