## Core Concept
The mandibular nerve (V3), a branch of the trigeminal nerve (cranial nerve V), divides into an anterior division and a posterior division. The anterior division primarily supplies muscles involved in mastication.

## Why the Correct Answer is Right
The muscles of mastication primarily supplied by the anterior division of the mandibular nerve include the **medial pterygoid**, **tensor tympani**, **tensor veli palatini**, and **masseter** and **anterior belly of digastric** (via the **masseteric nerve**, **deep temporal nerves**, and **nerve to medial pterygoid**). The **lateral pterygoid muscle** is also supplied by a branch from the anterior division.

## Why Each Wrong Option is Incorrect
- **Option A:** The **masseter muscle** is supplied by the masseteric nerve, a branch of the anterior division of the mandibular nerve.
- **Option B:** The **medial pterygoid muscle** is supplied by the nerve to medial pterygoid, which arises from the main trunk of the mandibular nerve or sometimes directly from the anterior division.
- **Option C:** The **anterior belly of digastric** is supplied by the mylohyoid nerve, a branch of the inferior alveolar nerve, which arises from the posterior division but is sometimes considered in the context of muscles related to the mandibular nerve supply.
- **Option D:** The **tensor tympani muscle** is supplied by the nerve to tensor tympani, which is a branch of the otic ganglion or directly from the mandibular nerve, reflecting its developmental origin related to the first pharyngeal arch.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the **mylohyoid nerve**, which supplies the **mylohyoid muscle** and the **anterior belly of the digastric muscle**, is a branch of the inferior alveolar nerve (from the posterior division of the mandibular nerve), making it an exception in the context of muscles supplied directly by branches of the anterior division.

## Correct Answer: C.