What is the most likely mechanism of injury when being rear-ended in a motor vehicle collision?

• A. Isolated cervical flexion
• B. Combined cervical extension and rotation
• C. Upper body rotation only
• D. Direct impact to the head

Answer: (B)

In a rear-ended motor vehicle collision, the most likely mechanism of injury is combined cervical extension and rotation. When a vehicle is struck from behind, the initial force causes the occupant's body to be thrust forward while the head snaps backward due to inertia. This movement can result in the neck extending beyond its normal range of motion, often accompanied by some degree of rotation of the head and upper body as the collision force is transmitted through the spine.

The combination of extension and rotation in this scenario can lead to various injuries, including whiplash, which commonly affects the cervical spine and can cause damage to soft tissue structures, such as muscles, ligaments, and intervertebral discs. Understanding this mechanism is critical for recognizing potential injuries associated with rear-end collisions and for appropriately diagnosing and treating conditions that may arise as a result.

The other options are less applicable because isolated cervical flexion would not be characteristic of a rear-ended scenario, as the initial movement is primarily extension. Upper body rotation alone does not adequately account for the forces at play during such an impact. Direct impact to the head may occur but is not the primary mechanism in most rear-end collisions, as the neck experiences a complex motion rather than just a straightforward blow.