All Sample Questions

Cleft Lip and Palate 1

Question

Vignette: A 2-month-old male infant is brought to the pediatrician by his concerned parents. They report that their child has been experiencing trouble feeding and has been gaining weight poorly. On physical examination, the pediatrician notes that the infant has a cleft lip and palate on the left side of his face.

Question: Which of the following best describes the embryological defect in this child?

Choices

A) Failure of the 1st and 2nd pharyngeal arches to fuse

B) Failure of the lateral nasal process to fuse with the maxillary process

C) Failure of the intermaxillary segment to fuse with the maxillary process

D) Failure of the medial nasal processes to fuse with each other

E) Failure of the medial nasal processes to fuse with the lateral nasal processes

Answer

C) Failure of the intermaxillary segment to fuse with the maxillary process

Explanation

The development of the face is a complex process that involves the fusion of several facial processes. The intermaxillary segment, which is derived from the fused medial nasal processes, forms the philtrum of the lip, four incisor teeth, and the primary palate. The maxillary processes, which are derived from the first pharyngeal arch, form the lateral parts of the upper lip and the secondary palate. A cleft lip and palate, as seen in this patient, results from a failure of the intermaxillary segment to fuse with the maxillary process. This results in a discontinuity in the upper lip and an opening between the oral and nasal cavities, which can lead to feeding difficulties and poor weight gain.