Which of the suprahyoid muscle is supplied by both facial nerve and mandibular nerve?
**Core Concept**
The question is testing the student's knowledge of the innervation of the suprahyoid muscles, specifically which muscle receives dual innervation from the facial nerve (cranial nerve VII) and the mandibular nerve (a branch of the trigeminal nerve, cranial nerve V3).
**Why the Correct Answer is Right**
The digastric muscle is unique in that it has two bellies: anterior and posterior. The anterior belly is innervated by the mylohyoid nerve, a branch of the mandibular nerve (cranial nerve V3), while the posterior belly is innervated by the facial nerve (cranial nerve VII). This dual innervation allows for coordinated movement of the digastric muscle during activities such as chewing and speaking.
**Why Each Wrong Option is Incorrect**
**Option A:** The mylohyoid muscle is primarily innervated by the mylohyoid nerve, a branch of the mandibular nerve (cranial nerve V3), and is not supplied by the facial nerve.
**Option B:** The geniohyoid muscle is primarily innervated by the hypoglossal nerve (cranial nerve XII) and is not supplied by the facial nerve or mandibular nerve.
**Option C:** The stylohyoid muscle is primarily innervated by the facial nerve (cranial nerve VII) and is not supplied by the mandibular nerve.
**Clinical Pearl / High-Yield Fact**
The digastric muscle's dual innervation is a classic example of a mixed nerve supply, highlighting the complex interplay between cranial nerves in the head and neck region.
**Correct Answer:** C. The digastric muscle.