A midline cleft lip is present when there is failure of fusion between the following structure:
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 cleftingRef: Losee J.E., Gimbel M., Rubin J., Wallace C.G., Wei F. (2010). Chapter 45. Plastic and Reconstructive Surgery. In F.C. Brunicardi, D.K. Andersen, T.R. Billiar, D.L. Dunn, J.G. Hunter, J.B. Matthews, R.E. Pollock (Eds), Schwaz's Principles of Surgery, 9e.
Mandibular processes
Medial nasal processes
Medial and lateral nasal process
Medial nasal and maxillary process.