Embryology: pharyngeal pouches: 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: pharyngeal pouches

Sample item

During parathyroidectomy for hyperparathyroidism, a surgeon finds an inferior parathyroid adenoma in the anterior mediastinum within the thymus. Which embryological fact explains this location?

AThe inferior parathyroid arises from the first pouch with the middle earBThe inferior parathyroid and thymus both arise from the third pouch and descend togetherCThe inferior parathyroid arises from the second pouch with the tonsilDThe inferior parathyroid arises from the fourth pouch with the ultimobranchial body

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

The answer and the reasoning

B. The inferior parathyroid and thymus both arise from the third pouch and descend together

The dorsal wing of the third pharyngeal pouch forms the inferior parathyroid and the ventral wing forms the thymus. As the thymus descends into the thorax it can drag the inferior parathyroid, which explains ectopic inferior glands in the anterior mediastinum. The superior parathyroid comes from the fourth pouch.

Option by option

A. The inferior parathyroid arises from the first pouch with the middle ear
The first pouch forms the tympanic cavity and auditory tube.
B. The inferior parathyroid and thymus both arise from the third pouch and descend together (correct)
Correct. Shared third-pouch origin explains the mediastinal position.
C. The inferior parathyroid arises from the second pouch with the tonsil
The second pouch forms the palatine tonsil epithelium.
D. The inferior parathyroid arises from the fourth pouch with the ultimobranchial body
The fourth pouch forms the superior parathyroid, which descends less.

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 B, The inferior parathyroid and thymus both arise from the third pouch and descend together. The dorsal wing of the third pharyngeal pouch forms the inferior parathyroid and the ventral wing forms the thymus.

Why is "The inferior parathyroid arises from the first pouch with the middle…" not the answer?

The first pouch forms the tympanic cavity and auditory tube.

Why is "The inferior parathyroid arises from the second pouch with the tonsil" not the answer?

The second pouch forms the palatine tonsil epithelium.

Why is "The inferior parathyroid arises from the fourth pouch with the ultimo…" not the answer?

The fourth pouch forms the superior parathyroid, which descends less.

What concept does this question test?

It tests Embryology: pharyngeal pouches in Anatomy. As the thymus descends into the thorax it can drag the inferior parathyroid, which explains ectopic inferior glands in the anterior mediastinum. The superior parathyroid comes from the fourth pouch.

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: pharyngeal pouches?

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.