Anatomy A 5-week-old male infant is born without a thymus or inferior parathyroid glands. Which of the following pharyngeal arches is most likely involved? A First B Second C Third D Fourth 💡 Explanation A 5-week-old male infant is born without a thymus or inferior parathyroid glands. Which of the following pharyngeal arches is most likely involved? ✓ Correct Answer: C. Third