USMLE STEP 1 QUESTION

CONCEPT: Aortic arch embryology

A 3-year-old boy is brought to the pediatrician by his mother due to recurrent episodes of difficulty swallowing and breathing. On physical examination, his vital signs are as follows: Temperature 98.6°F (37°C), pulse 95/min, respirations 25/minute, and blood pressure 95/60 mmHg. His oxygen saturation is 97% on room air. The physician orders a chest X-r…