Temporomandibular joint: dislocation: 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 · Temporomandibular joint: dislocation

Sample item

A 30-year-old woman yawns widely and cannot close her mouth. The mandibular heads lie in front of the articular tubercles. Which muscle is mainly responsible for pulling the head forward?

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

The answer and the reasoning

C. Lateral pterygoid

The lateral pterygoid inserts into the neck of the mandible and the articular disc, and pulls the condyle and disc forward over the articular tubercle when the mouth opens widely. In excessive opening the head can slip in front of the tubercle and the elevator muscles go into spasm, locking the jaw. The usual dislocation is anterior and bilateral.

Option by option

  • A. Posterior fibres of temporalis

    The posterior fibres of temporalis retract the mandible.

  • B. Medial pterygoid

    The medial pterygoid elevates the mandible and helps closure.

  • C. Lateral pterygoid (correct)

    Correct. The lateral pterygoid draws the condyle and disc forward.

  • D. Masseter

    The masseter elevates the mandible and does not protract the condyle.

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, Lateral pterygoid. The lateral pterygoid inserts into the neck of the mandible and the articular disc, and pulls the condyle and disc forward over the articular tubercle when the mouth opens widely.

Why is "Posterior fibres of temporalis" not the answer?

The posterior fibres of temporalis retract the mandible.

Why is "Medial pterygoid" not the answer?

The medial pterygoid elevates the mandible and helps closure.

Why is "Masseter" not the answer?

The masseter elevates the mandible and does not protract the condyle.

What concept does this question test?

It tests Temporomandibular joint: dislocation in Anatomy. In excessive opening the head can slip in front of the tubercle and the elevator muscles go into spasm, locking the jaw. The usual dislocation is anterior and bilateral.

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 Temporomandibular joint: dislocation?

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.