Brachial plexus: musculocutaneous nerve: 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 · Brachial plexus: musculocutaneous nerve

Sample item

A man sustains a deep stab wound to the front of the upper arm. He has weakness of elbow flexion with the forearm in supination, a lost biceps reflex and numbness over the lateral forearm. Which nerve is injured?

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

The answer and the reasoning

B. Musculocutaneous nerve

The musculocutaneous nerve pierces coracobrachialis and supplies coracobrachialis, biceps brachii and brachialis. It then continues as the lateral cutaneous nerve of the forearm. Injury weakens elbow flexion, especially in supination, abolishes the biceps jerk and causes sensory loss on the lateral forearm.

Option by option

  • A. Axillary nerve

    The axillary nerve supplies deltoid and the skin over the lower deltoid.

  • B. Musculocutaneous nerve (correct)

    Correct. Loss of the three flexors and the lateral forearm skin points to the musculocutaneous nerve.

  • C. Radial nerve

    The radial nerve supplies the extensors, although brachioradialis would weaken flexion in the mid-prone position.

  • D. Median nerve

    The median nerve does not supply the arm flexors and causes forearm and hand deficits.

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, Musculocutaneous nerve. The musculocutaneous nerve pierces coracobrachialis and supplies coracobrachialis, biceps brachii and brachialis.

Why is "Axillary nerve" not the answer?

The axillary nerve supplies deltoid and the skin over the lower deltoid.

Why is "Radial nerve" not the answer?

The radial nerve supplies the extensors, although brachioradialis would weaken flexion in the mid-prone position.

Why is "Median nerve" not the answer?

The median nerve does not supply the arm flexors and causes forearm and hand deficits.

What concept does this question test?

It tests Brachial plexus: musculocutaneous nerve in Anatomy. It then continues as the lateral cutaneous nerve of the forearm. Injury weakens elbow flexion, especially in supination, abolishes the biceps jerk and causes sensory loss on the lateral forearm.

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 Brachial plexus: musculocutaneous nerve?

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.