Arm: 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 · Arm: musculocutaneous nerve

Sample item

After an anterior shoulder dislocation a man has weak elbow flexion with the forearm supinated, an absent biceps jerk and numbness along the lateral side of the forearm. Which nerve is injured and what is its terminal cutaneous branch?

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

The answer and the reasoning

C. Musculocutaneous nerve; lateral cutaneous nerve of the forearm

The musculocutaneous nerve (C5 to C7) pierces coracobrachialis and supplies coracobrachialis, biceps and brachialis. It continues as the lateral cutaneous nerve of the forearm, which supplies skin of the lateral forearm. Loss of biceps and brachialis weakens flexion and supination.

Option by option

  • A. Median nerve; palmar cutaneous branch

    The median palmar cutaneous branch supplies the proximal palm, not the forearm.

  • B. Axillary nerve; upper lateral cutaneous nerve of the arm

    The axillary nerve supplies deltoid and the skin over the lower deltoid, not the forearm.

  • C. Musculocutaneous nerve; lateral cutaneous nerve of the forearm (correct)

    Correct. Motor loss to biceps and brachialis with lateral forearm numbness identifies this nerve.

  • D. Radial nerve; posterior cutaneous nerve of the forearm

    The radial nerve supplies the extensors; its brachioradialis is only a minor elbow flexor, and it does not explain the absent biceps jerk or lateral forearm numbness.

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 C, Musculocutaneous nerve; lateral cutaneous nerve of the forearm. The musculocutaneous nerve (C5 to C7) pierces coracobrachialis and supplies coracobrachialis, biceps and brachialis.

Why is "Median nerve; palmar cutaneous branch" not the answer?

The median palmar cutaneous branch supplies the proximal palm, not the forearm.

Why is "Axillary nerve; upper lateral cutaneous nerve of the arm" not the answer?

The axillary nerve supplies deltoid and the skin over the lower deltoid, not the forearm.

Why is "Radial nerve; posterior cutaneous nerve of the forearm" not the answer?

The radial nerve supplies the extensors; its brachioradialis is only a minor elbow flexor, and it does not explain the absent biceps jerk or lateral forearm numbness.

What concept does this question test?

It tests Arm: musculocutaneous nerve in Anatomy. It continues as the lateral cutaneous nerve of the forearm, which supplies skin of the lateral forearm. Loss of biceps and brachialis weakens flexion and supination.

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 Arm: 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.