Figure 1

Physical measurements in the neutral position. 1: Hyomental distance (HMD): Distance between the chin and the hyoid bone. 2: Direct thyromental distance (DTMD): Distance between the chin and the thyroid cartilage. 3: Vertical thyromental distance (VTMD): Vertical distance between the chin and the thyroid cartilage. 4: Horizontal thyromental distance (HTMD): Horizontal distance between the chin and the thyroid cartilage. 5: Sternomental distance (SMD): Distance between the chin and the sternum.