Jillian is thrown from a horse. She strikes the ground with her chin, causing severehyperextensionof the neck. Emergency medical technicians properly immobilize her neck and transport her to a hospital, but she dies 5 minutes after arrival. An autopsy shows multiple fractures of vertebrae C1, C6, and C7 and extensive damage to the spinal cord. Explain why she died rather than being left a quadriplegic.