Abdomen and pelvis: caudal epidural block: 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 · Abdomen and pelvis: caudal epidural block

Sample item

A 5-year-old child has a caudal epidural block for herniotomy. After palpating the sacral cornua, the needle gives a characteristic give as it enters the sacral canal. Which structure has just been pierced?

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

The answer and the reasoning

B. Sacrococcygeal membrane

The sacral hiatus is closed by the sacrococcygeal membrane, which stretches between the sacral cornua. The needle pierces it to enter the sacral canal containing epidural fat and the sacral nerve roots. The dural sac usually ends at about S2.

Option by option

  • A. Sacrotuberous ligament

    This ligament passes from the sacrum to the ischial tuberosity and is not on the needle path.

  • B. Sacrococcygeal membrane (correct)

    Correct. This membrane covers the sacral hiatus and is the structure pierced.

  • C. Posterior longitudinal ligament

    This ligament lies on the anterior wall of the vertebral canal, not behind the sacral hiatus.

  • D. Interspinous ligament

    This ligament lies between spinous processes in the vertebral column, not at the sacral hiatus.

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 B, Sacrococcygeal membrane. The sacral hiatus is closed by the sacrococcygeal membrane, which stretches between the sacral cornua.

Why is "Sacrotuberous ligament" not the answer?

This ligament passes from the sacrum to the ischial tuberosity and is not on the needle path.

Why is "Posterior longitudinal ligament" not the answer?

This ligament lies on the anterior wall of the vertebral canal, not behind the sacral hiatus.

Why is "Interspinous ligament" not the answer?

This ligament lies between spinous processes in the vertebral column, not at the sacral hiatus.

What concept does this question test?

It tests Abdomen and pelvis: caudal epidural block in Anatomy. The needle pierces it to enter the sacral canal containing epidural fat and the sacral nerve roots. The dural sac usually ends at about S2.

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 Abdomen and pelvis: caudal epidural block?

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.