Head and Neck Anatomical Structures · USMLE Step 1

A patient presents with inability to retract the mandible. Dysfunction of which muscle is most likely responsible?

  1. Lateral pterygoid (jaw protrusion)
  2. Masseter (jaw elevation)
  3. Temporalis (posterior fibers)
  4. Medial pterygoid (jaw elevation)
Show answer and explanation

Correct answer: Temporalis (posterior fibers)

The posterior fibers of temporalis are the primary retractors of the mandible. Injury impairs retraction while leaving elevation mostly intact.

Difficulty: Medium Question 2 of 20

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