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

The question pertains to the deviation of the mandible following hemimandibulectomy. To determine the muscle responsible for this deviation, we must consider the anatomy and function of the muscles involved in mastication.

When a hemimandibulectomy is performed, one side of the mandible is removed, which can lead to an imbalance in the force distribution among the muscles on each side.

1. The Medial pterygoid muscle primarily functions to elevate the mandible and assist in protrusion. It also plays a role in moving the mandible laterally.
2. The Lateral pterygoid muscle helps in opening the jaw and protruding the mandible by pulling the neck of the mandible forward. It also aids in lateral deviation when acting unilaterally.
3. The Masseter is a powerful elevator of the mandible, contributing to the closing of the jaw and stabilization.
4. The Temporalis functions to elevate and retract the mandible, maintaining closure of the jaw.

In the event of a hemimandibulectomy, the deviation of the mandible occurs towards the side of the surgery. This happens because the opposite side's muscles are unopposed. The primary muscle responsible for pulling the mandible towards the surgical side is the Medial pterygoid because its contraction on the intact side pulls the mandible towards the ipsilateral side.

Therefore, the muscle responsible for the deviation of the mandible towards the operated side after hemimandibulectomy is the Medial pterygoid.