Brachial plexus: 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

Sample item

A newborn delivered after a difficult shoulder dystocia holds the arm adducted, internally rotated and extended, the 'waiter's tip' posture. Which part of the brachial plexus is injured?

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

The answer and the reasoning

B. Upper trunk (C5–C6)

Erb's palsy is an upper trunk injury. The loss of deltoid, supraspinatus, infraspinatus, biceps and brachialis leaves the shoulder adducted and internally rotated and the forearm pronated.

Option by option

  • A. Posterior cord

    Posterior cord injury affects the axillary and radial nerves and is rare in newborns.

  • B. Upper trunk (C5–C6) (correct)

    Correct. Forceful lateral traction of the neck stretches the upper trunk.

  • C. Lateral cord

    A lateral cord injury would mostly affect musculocutaneous and lateral median fibres.

  • D. Lower trunk (C8–T1)

    Lower trunk injury (Klumpke) gives a claw hand and sometimes Horner syndrome.

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, Upper trunk (C5–C6). Erb's palsy is an upper trunk injury.

Why is "Posterior cord" not the answer?

Posterior cord injury affects the axillary and radial nerves and is rare in newborns.

Why is "Lateral cord" not the answer?

A lateral cord injury would mostly affect musculocutaneous and lateral median fibres.

Why is "Lower trunk (C8–T1)" not the answer?

Lower trunk injury (Klumpke) gives a claw hand and sometimes Horner syndrome.

What concept does this question test?

It tests Brachial plexus in Anatomy. The loss of deltoid, supraspinatus, infraspinatus, biceps and brachialis leaves the shoulder adducted and internally rotated and the forearm pronated.

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?

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.