WBR0335

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Embryology
Sub Category	SubCategory::Head and Neck
Prompt	[[Prompt::An 8 month old boy is brought by his mother to the physician's office for a facial abnormality that she wishes to be corrected. A patient with a similar abnormality is shown in the image below. The physician explains that the boy has an embryological defect. Which of the following processes failed to occur in this patient? ]]
Answer A	AnswerA::Failure of fusion of the maxillary and medial nasal processes
Answer A Explanation	AnswerAExp::Cleft lip is characterized by the failure of fusion of the maxillary and medial nasal processes.
Answer B	AnswerB::Failure of fusion of the maxillary and lateral nasal processes
Answer B Explanation	AnswerBExp::Cleft lip is not characterized by the failure of fusion of the maxillary and lateral nasal processes.
Answer C	AnswerC::Failure of fusion of the mandibular and the medial nasal processes
Answer C Explanation	AnswerCExp::Cleft lip is not characterized by the failure of fusion of the mandibular and the medial nasal processes.
Answer D	AnswerD::Failure of fusion of the mandibular and the lateral nasal processes
Answer D Explanation	AnswerDExp::Cleft lip is not characterized by the failure of fusion of the mandibular and the lateral nasal processes.
Answer E	AnswerE::Failure of fusion of the maxillary and the palatine processes
Answer E Explanation	[[AnswerEExp::Although cleft palate frequently occurs with cleft lip, cleft palate is due to failure of fusion of the lateral palatine processes, the nasal septum, and the median palatine process. Failure of fusion of the maxillary and the palatine processes are not characteristic of either cleft lip or cleft palate.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::The patient is most likely presenting with cleft lip with or without cleft palate. Cleft lip is characterized by the failure of fusion (non-union) of the maxillary and the medial nasal processes. On the other hand, cleft palate is characterized by the failure of fusion of the lateral palatine processes, the nasal septum, and the median palatine processes. Usually cleft lip and cleft palate happen together although they occur due to different embryological pathophysiological processes. Educational Objective: Cleft palate is characterized by the failure of fusion of the maxillary and the median nasal processes. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::cleft, WBRKeyword::lip, WBRKeyword::palate, WBRKeyword::failure, WBRKeyword::fusion, WBRKeyword::median, WBRKeyword::medial, WBRKeyword::nasal, WBRKeyword::process, WBRKeyword::processes, WBRKeyword::maxillary, WBRKeyword::lateral, WBRKeyword::palatine, WBRKeyword::nasal, WBRKeyword::septum, WBRKeyword::facial, WBRKeyword::abnormality
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::