Question

After hemimandibulectomy, the mandible deviates on one side. Which of the following muscles is responsible for this?

• A. Medial pterygoid
• B. Lateral pterygoid
• C. Masseter
• D. Temporalis

Hint:

After hemimandibulectomy, mandibular deviation occurs due to imbalance of masticatory muscles, especially the medial pterygoid.

Answer 1

The Correct Option is A

Step 1: Understanding Hemimandibulectomy.
Hemimandibulectomy involves surgical removal of one half of the mandibleAfter surgery, the balance of muscular forces acting on the mandible is disturbedThis results in deviation of the mandible toward one side
Step 2: Role of Muscles in Mandibular Movement.
The muscles of mastication (masseter, temporalis, medial pterygoid, and lateral pterygoid) act in coordination to maintain symmetrical mandibular movementAmong these, the medial pterygoid plays an important role in elevation and maintaining medial stability of the mandible
Step 3: Mechanism of Deviation.
After removal of one side of the mandible, the unopposed pull of the medial pterygoid muscle on the intact side causes deviation of the mandible toward the resected sideLoss of counterbalancing muscle forces leads to this characteristic deviation
Step 4: Evaluation of Options.
(A) Medial pterygoid: CorrectIt contributes significantly to deviation due to imbalance of muscular forces
(B) Lateral pterygoid: Mainly responsible for protrusion and side-to-side movement
(C) Masseter: Elevates mandible but is not primarily responsible for deviation in this context
(D) Temporalis: Elevates and retracts mandible but not the primary cause of deviation here
Step 5: Conclusion.
Therefore, the medial pterygoid muscle is responsible for deviation of the mandible after hemimandibulectomy