Upper limb and brachial plexus: boutonniere deformity: 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 and brachial plexus: boutonniere deformity

Sample item

A laceration over the dorsum of a finger is followed by a flexed proximal interphalangeal joint and hyperextended distal joint. Which structure was divided?

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

The answer and the reasoning

C. Central slip of the extensor expansion

Division of the central slip stops extension at the proximal interphalangeal joint. The lateral bands then slip volar to the joint axis and pull on the distal phalanx, causing a boutonniere deformity with proximal flexion and distal hyperextension.

Option by option

  • A. Flexor digitorum superficialis tendon

    Division of this tendon weakens proximal flexion and does not produce proximal flexion with distal hyperextension.

  • B. Terminal extensor tendon

    Division here causes mallet finger, with a drooping distal joint.

  • C. Central slip of the extensor expansion (correct)

    Correct. Central slip loss gives proximal flexion with distal hyperextension.

  • D. Oblique retinacular ligament

    This ligament links the two interphalangeal joints and its loss does not cause this posture.

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.

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Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is C, Central slip of the extensor expansion. Division of the central slip stops extension at the proximal interphalangeal joint.

Why is "Flexor digitorum superficialis tendon" not the answer?

Division of this tendon weakens proximal flexion and does not produce proximal flexion with distal hyperextension.

Why is "Terminal extensor tendon" not the answer?

Division here causes mallet finger, with a drooping distal joint.

Why is "Oblique retinacular ligament" not the answer?

This ligament links the two interphalangeal joints and its loss does not cause this posture.

What concept does this question test?

It tests Upper limb and brachial plexus: boutonniere deformity in Anatomy. The lateral bands then slip volar to the joint axis and pull on the distal phalanx, causing a boutonniere deformity with proximal flexion and distal hyperextension.

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 and brachial plexus: boutonniere deformity?

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.