All of the following structures develops from 2nd brachial arch, EXCEPT:
The second branchial arch forms bony and muscular structures from the ear (proximally) to the hyoid bone (distally), including the muscles of facial expression that are innervated by the facial nerve (cranial nerve (CN) VII). The posterior belly of digastric muscle develops from the mesoderm of second branchial arch hence it is supplied by the facial nerve. The anterior belly develops from the mesoderm of first branchial arch and hence supplied by mandibular nerve.
Buccinator
7th cranial nerve
Anterior belly of digastric
Stapes