Upper limb: radial nerve in the spiral groove: 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: radial nerve in the spiral groove

Sample item

A 30-year-old man sustains a fracture of the mid-shaft of the humerus in a road accident. He has wrist drop and loss of sensation over the dorsum of the first web space, yet he can extend his elbow against resistance. Why is elbow extension preserved?

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

The answer and the reasoning

A. The triceps branches leave the radial nerve in the axilla and proximal arm, above the groove

The radial nerve gives off its main branches to the triceps in the axilla and proximal arm, before it enters the spiral groove. A mid-shaft humeral fracture therefore causes wrist drop and sensory loss but spares most elbow extension. A lesion in the axilla would paralyse the triceps as well.

Option by option

  • A. The triceps branches leave the radial nerve in the axilla and proximal arm, above the groove (correct)

    Correct. The triceps branches arise proximal to the site of injury and are not damaged.

  • B. The triceps is supplied by the axillary nerve, which lies above the fracture

    The axillary nerve supplies deltoid and teres minor, not triceps.

  • C. Elbow extension is carried out entirely by the anconeus, supplied by the ulnar nerve

    The anconeus is supplied by the radial nerve, and the ulnar nerve does not extend the elbow.

  • D. The triceps is supplied by the musculocutaneous nerve, which is intact

    The musculocutaneous nerve supplies the flexors of the elbow (biceps, brachialis and coracobrachialis).

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, The triceps branches leave the radial nerve in the axilla and proximal arm, above the groove. The radial nerve gives off its main branches to the triceps in the axilla and proximal arm, before it enters the spiral groove.

Why is "The triceps is supplied by the axillary nerve, which lies above the f…" not the answer?

The axillary nerve supplies deltoid and teres minor, not triceps.

Why is "Elbow extension is carried out entirely by the anconeus, supplied by…" not the answer?

The anconeus is supplied by the radial nerve, and the ulnar nerve does not extend the elbow.

Why is "The triceps is supplied by the musculocutaneous nerve, which is intact" not the answer?

The musculocutaneous nerve supplies the flexors of the elbow (biceps, brachialis and coracobrachialis).

What concept does this question test?

It tests Upper limb: radial nerve in the spiral groove in Anatomy. A mid-shaft humeral fracture therefore causes wrist drop and sensory loss but spares most elbow extension. A lesion in the axilla would paralyse the triceps as well.

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 Upper limb: radial nerve in the spiral groove?

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.