Local and regional anaesthesia: interscalene block distribution: practice question

A Anaesthesia 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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Anaesthesia · Local and regional anaesthesia: interscalene block distribution

Sample item

After an interscalene block for shoulder surgery, the shoulder is anaesthetised but the little finger and the ulnar border of the hand remain sensate. Which dermatomes are typically spared?

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

The answer and the reasoning

D. C8 and T1

The interscalene approach blocks the upper and middle trunks, giving good cover of C5 to C7 but often sparing the lower trunk, C8 and T1, which supply the ulnar border. It is therefore unsuitable for hand surgery. A supraclavicular or infraclavicular block covers the lower trunk better.

Option by option

  • A. C6 and C7

    C6 and C7 are covered by the block.

  • B. C4 and C5

    C4 and C5 supply the shoulder cap and are covered.

  • C. C5 and C6

    C5 and C6 supply the shoulder and lateral arm, which are blocked well.

  • D. C8 and T1 (correct)

    Correct. C8 and T1 form the lower trunk and are often missed.

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.

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Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is D, C8 and T1. The interscalene approach blocks the upper and middle trunks, giving good cover of C5 to C7 but often sparing the lower trunk, C8 and T1, which supply the ulnar border.

Why is "C6 and C7" not the answer?

C6 and C7 are covered by the block.

Why is "C4 and C5" not the answer?

C4 and C5 supply the shoulder cap and are covered.

Why is "C5 and C6" not the answer?

C5 and C6 supply the shoulder and lateral arm, which are blocked well.

What concept does this question test?

It tests Local and regional anaesthesia: interscalene block distribution in Anaesthesia. It is therefore unsuitable for hand surgery. A supraclavicular or infraclavicular block covers the lower trunk better.

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 Local and regional anaesthesia: interscalene block distribution?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia 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.