Oral Surgery · single question
During a mandibular deviation to the left on mouth opening (no pain, 32mm opening), which muscle is most likely affected?
Show answer and explanation
Correct answer: C. Left lateral pterygoid (affected/weak side)
- A. A weak right lateral pterygoid would cause deviation to the RIGHT, not the left.
- B. The temporalis is primarily an elevator/retractor; its dysfunction alone does not cause ipsilateral deviation on opening.
- C. Correct. On opening, the mandible deviates TOWARD the affected/weak side. If the mandible deviates to the LEFT, the LEFT lateral pterygoid is weak or dysfunctional — the right side pulls unopposed, causing leftward deviation.
- D. The masseter is an elevator; its dysfunction does not cause the deviation pattern described.