Final answer:
In a head-on, up and over collision, an unrestrained driver may sustain severe skeletal system injuries, including various types of fractures, and potential traumatic brain injuries due to sudden impact with the vehicle's interior components.
Step-by-step explanation:
An unrestrained driver involved in a head-on, up and over collision will likely sustain multiple injuries, predominantly to the skeletal system. Without the protection of seatbelts and airbags, the driver would make an abrupt and forceful contact with the steering wheel and dashboard. In such collisions, head and traumatic brain injuries are prevalent, which might result in fractures like linear skull fractures, comminuted fractures (where the bone is broken into pieces), depressed fractures (where fractured bones are pushed inward), and contrecoup fractures (fractures on the opposite side of the skull from the impact). Injuries such as basilar fractures at the base of the skull could damage the artery passing through the carotid canal, leading to bleeding and potential brain damage. Other injuries could include damage to the knees, such as anterior cruciate ligament injuries resulting from hyperextension or twisting forces.