Figure 6. Distribution of individual patient data points for three representative stages in the intubation sequence. The preinsertion, tube, and postintubation stages are portrayed here to delineate the extremes of segmental cervical motion created by direct laryngoscopy. Note that the variability in motion is greatest at the occipitoatlantal (A) and atlantoaxial (B) articulations, and is substantially less in the subaxial motion segments such as the C3-C4 articulation (C).