Embryology: stomach rotation: 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: stomach rotation

Sample item

At vagotomy a surgeon finds that the anterior vagal trunk is derived mainly from the left vagus nerve and the posterior trunk from the right. Which embryological event explains this arrangement?

AA 90 degree clockwise rotation of the stomachBFusion of the dorsal mesogastrium to the posterior wallCA 90 degree anticlockwise rotation of the stomachDA 180 degree clockwise rotation of the midgut loop

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

The answer and the reasoning

A. A 90 degree clockwise rotation of the stomach

The stomach rotates 90 degrees clockwise about its long axis, viewed from above. The left side becomes anterior and the right side posterior, so the left vagus supplies the anterior surface and the right vagus the posterior surface.

Option by option

A. A 90 degree clockwise rotation of the stomach (correct)
Correct. A clockwise quarter turn brings the left vagus anteriorly.
B. Fusion of the dorsal mesogastrium to the posterior wall
Fusion of the dorsal mesogastrium relates to the pancreas and does not reposition the vagal trunks.
C. A 90 degree anticlockwise rotation of the stomach
An anticlockwise turn would place the right vagus anteriorly, the opposite of what is found.
D. A 180 degree clockwise rotation of the midgut loop
Midgut loop rotation affects the intestine, not the vagal trunks on the stomach.

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 A, A 90 degree clockwise rotation of the stomach. The stomach rotates 90 degrees clockwise about its long axis, viewed from above.

Why is "Fusion of the dorsal mesogastrium to the posterior wall" not the answer?

Fusion of the dorsal mesogastrium relates to the pancreas and does not reposition the vagal trunks.

Why is "A 90 degree anticlockwise rotation of the stomach" not the answer?

An anticlockwise turn would place the right vagus anteriorly, the opposite of what is found.

Why is "A 180 degree clockwise rotation of the midgut loop" not the answer?

Midgut loop rotation affects the intestine, not the vagal trunks on the stomach.

What concept does this question test?

It tests Embryology: stomach rotation in Anatomy. The left side becomes anterior and the right side posterior, so the left vagus supplies the anterior surface and the right vagus the posterior surface.

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: stomach rotation?

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.