Injury to the motor division of the mandibular nerve will cause paralysis of the following except:
**Core Concept**
The mandibular nerve is a branch of the trigeminal nerve (cranial nerve V), which has both sensory and motor divisions. The motor division of the mandibular nerve supplies the muscles of mastication, including the medial pterygoid, lateral pterygoid, masseter, and temporalis. Injury to this division can lead to weakness or paralysis of these muscles.
**Why the Correct Answer is Right**
The correct answer is related to the muscles of mastication. The medial pterygoid, lateral pterygoid, masseter, and temporalis muscles are responsible for jaw movement and mastication. The motor division of the mandibular nerve provides the nerve supply to these muscles, enabling them to function properly. Injury to this division can lead to weakness or paralysis of these muscles, resulting in difficulties with chewing and biting.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the medial pterygoid muscle is supplied by the motor division of the mandibular nerve. Injury to this division can lead to weakness or paralysis of this muscle.
* **Option B:** This option is incorrect because the lateral pterygoid muscle is also supplied by the motor division of the mandibular nerve. Injury to this division can lead to weakness or paralysis of this muscle.
* **Option C:** This option is incorrect because the masseter muscle is supplied by the motor division of the mandibular nerve. Injury to this division can lead to weakness or paralysis of this muscle.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the motor division of the mandibular nerve supplies the muscles of mastication, and injury to this division can lead to weakness or paralysis of these muscles, resulting in difficulties with chewing and biting.
**Correct Answer:** D