A 46-year-old man is brought to the emergency department after a motor vehicle collision. He is intubated for airway protection. Over the next hour, the ventilator alarm sounds repeatedly because the patient is initiating prolonged inspiratory efforts with large tidal volumes and a slow respiratory rate despite stable oxygenation. Neurologic exam shows decreased corneal reflex on the right and reduced sensation to light touch over the right cheek and jaw; jaw deviation is noted when he is briefly awakened. A head CT shows a small hemorrhagic contusion in the dorsal upper pons abutting the floor of the fourth ventricle.

Which structure is most likely injured, and what is its primary role in respiratory control?