Digastric Posterior Belly — MFDS Part 1 MCQ
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Correct answer: A — Facial nerve (VII)
The correct answer is A: the facial nerve (VII). A digastric branch arises from the facial nerve after it exits the stylomastoid foramen and supplies the posterior belly, consistent with that muscle's second pharyngeal arch origin. By contrast, the anterior belly is a first-arch muscle supplied by the nerve to mylohyoid, a branch of the inferior alveolar nerve from V3. The hypoglossal nerve supplies most intrinsic and extrinsic tongue muscles, while the glossopharyngeal nerve provides motor innervation to stylopharyngeus. The ansa cervicalis supplies most infrahyoid muscles and does not innervate either belly of the digastric. Thus, the distinction between the embryological origins and innervation of the two digastric bellies is decisive.
Reference: Monkhouse WS. The anatomy of the facial nerve. Ear Nose Throat Journal. 1990;69(10):677–683, 686–687. https://pubmed.ncbi.nlm.nih.gov/2286163/