abnormal pharyngeal arch morphology abnormal second pharyngeal arch morphology MP:0006338 MPheno.ontology abnormal hyoid arch morphology abnormal second branchial arch morphology any structural anomaly of the second arch which contributes to the development of the stapes, styloid process, hyoid bone, stylohyoid ligament, muscles of facial expression, stapedius muscle, stylohyoid muscle, and lining of the palatine tonsils