YW is a 23 year-old male student from Thailand studying electrical engineering at the university. He was ejected from a moving vehicle, which was traveling 70 mph. His injuries included a severe closed head injury with an occipitalhematoma, bilateral wrist fractures, and a right pneumothorax. During his neurologic intensive care unit (NICU) stay. YW was intubated and placed on mechanical ventilation, had a feeding tube inserted and was placed on tube feedings, had a Foley catheter to down drain (DD), and had multiple IVs inserted. He developed pneumonia 1 month after admission.

Question 1:Define the term primary head injury