A midline cleft lip is present when there is failure of fusion between the following structure?: (A) Mandibular processes, (B) Medial nasal processes, (C) Medial and lateral nasal process, (D) Medial nasal and maxillary process.
Answer is B. Clefting of the lip and/or palate is felt to occur around the eighth week of embryogenesis, either by failure of fusion of the medial nasal process and the maxillary prominence or by failure of mesodermal migration and penetration between the epithelial bilayer of the face. The cause of orofacial clefting is felt to be multifactorial. Factors that likely increase the incidence of clefting include,Increased parental ageDrug useInfections during pregnancySmoking during pregnancyFamily history of orofacial clefting.