Figure 3

Frequency distributions of head inclination. Comparison of histograms of the fractions of time with head inclination in the sagittal (above) or lateral plane (below) for operations with direct and monitor endoscopy - mean and standard deviation (direct endoscopy: n = 10, monitor endoscopy: n = 9), * = significantly different (p < 0.05). Specifications of the head inclination angles are provided in the insets.