Upper limb: median 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 · Upper limb: median nerve

Sample item

After a supracondylar fracture a man cannot flex the thumb, index and middle fingers and has weak forearm pronation. When he tries to make a fist the index and middle fingers stay extended. There is sensory loss over the lateral three and a half digits of the palm. Where is the lesion?

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

The answer and the reasoning

A. At or just above the elbow, proximal to the branch to pronator teres

A proximal median lesion paralyses the pronators, wrist and finger flexors supplied by the nerve, giving the hand of benediction on attempted fist and loss of palmar sensation. Weak pronation shows that the branch to pronator teres, given off near the elbow, is involved. At the wrist, pronation and long flexors are spared.

Option by option

  • A. At or just above the elbow, proximal to the branch to pronator teres (correct)

    Correct. Loss of pronation, finger flexion and median sensation places the lesion at or above the elbow.

  • B. In the anterior interosseous branch in the proximal forearm

    An anterior interosseous lesion has no sensory loss and pronator teres is spared.

  • C. In the posterior interosseous nerve at the supinator

    The posterior interosseous nerve is motor to the extensors and does not cause flexor weakness or sensory loss.

  • D. At the carpal tunnel behind the flexor retinaculum

    A carpal tunnel lesion causes thenar weakness and sensory loss but spares pronation and long finger flexors.

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 A, At or just above the elbow, proximal to the branch to pronator teres. A proximal median lesion paralyses the pronators, wrist and finger flexors supplied by the nerve, giving the hand of benediction on attempted fist and loss of palmar sensation.

Why is "In the anterior interosseous branch in the proximal forearm" not the answer?

An anterior interosseous lesion has no sensory loss and pronator teres is spared.

Why is "In the posterior interosseous nerve at the supinator" not the answer?

The posterior interosseous nerve is motor to the extensors and does not cause flexor weakness or sensory loss.

Why is "At the carpal tunnel behind the flexor retinaculum" not the answer?

A carpal tunnel lesion causes thenar weakness and sensory loss but spares pronation and long finger flexors.

What concept does this question test?

It tests Upper limb: median nerve in Anatomy. Weak pronation shows that the branch to pronator teres, given off near the elbow, is involved. At the wrist, pronation and long flexors are spared.

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 Upper limb: median 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.