Question

Which structure is derived from the first pharyngeal arch?

• A. Levator palatini
• B. Buccinator
• C. Stylohyoid
• D. Anterior belly of digastric

Hint:

First arch muscles are supplied by the trigeminal nerve; which option fits that?

Answer 1

The Correct Option is D

Step 1: The first (mandibular) pharyngeal arch is supplied by the trigeminal nerve and gives rise to the muscles of mastication plus the mylohyoid, anterior belly of digastric, tensor veli palatini and tensor tympani.
Step 2: The anterior belly of digastric is therefore a first arch derivative, supplied by the mylohyoid branch of the mandibular division of the trigeminal nerve.
Step 3: The distractors belong to other arches. Stylohyoid and the muscles of facial expression (and posterior belly of digastric) are second arch derivatives supplied by the facial nerve. Buccinator is also a second arch muscle of facial expression. Levator veli palatini is a fourth arch derivative.
Step 4: Hence the correct answer is anterior belly of digastric.