Final answer:
When securing a patient to a spinal immobilization device, the head should be secured first.
Step-by-step explanation:
When securing a patient to a spinal immobilization device, the head should be secured first. The head is the most crucial part to support and stabilize to prevent further injury to the spinal cord. Once the head is secured, the other parts of the body can be properly immobilized, starting from the chest, then the legs, and finally the arms.