On each image, lines will be drawn to mark the relative position of the occiput, atlas (C1), axis (C2) and the fifth cervical vertebra (C5). The angle between each of these lines will be measured to determine the degree of angulation of C1, C2 and C5 relative to the occiput and each other. [9] The radiographs will be reviewed by a radiology consultant who will be blinded to the order of intubation technique and unfamiliar with the laryngoscopes being used.