Review Question - QID 109409

A 8-month-old boy is brought to the emergency department by his mother and father due to decreasing activity and excessive sleepiness. The patient was born at full-term in the hospital with no complications. The patient's parents appear incredibly worried as their son has had no medical issues in the past. They show you videos of the child happily playing with his parents the day before. The patient’s mother states that the patient hit his head while crawling this morning and since then has been difficult to arouse. His mother is worried because she thinks he had a fever earlier in the day and he was clutching his head and neck in pain. Physical examination shows a barely arousable boy with a large, full anterior fontanelle. The boy grimaces on palpation of his chest, and a radiograph show posterior rib fractures. Retinal examination shows bilateral retinal hemorrhages. Which of the following is the most likely cause for this patient’s presentation?