How should a lateral cervical spine film be read?

1. All seven cervical vertebrae should be well visualized - count down to vertebra T1.

2. Check the thickness of the retropharyngeal/retrotracheal space.

3. Assess the four parallel lines for disconti-nuity or step-off.

4. Examine the atlantodental interval (i.e., the distance from the anterior arch of C1 to the odontoid process of C2).

5. Scrutinize the disc spaces for narrowing or widening caused by acute injury.