Fig. 1

Thyroid cartilage contour showing the main measurement points. a-apex of the superior horn; b-point at the base of superior horn; c-point at the base of inferior horn; d-apex of inferior horns; E-superior point of anterior intermedium line; f-inferior point of the anterior intermedium line; g-superior point of lamina middle line; h-inferior point of lamina middle line; k-point in the middle of right lamina’s posterior edge; l-point in the middle of right lamina’s anterior edge; m-point in the middle of left lamina’s anterior edge; n-point in the middle of left lamina’s posterior edge; P-middle of the line connecting the upper edge of the left and right thyroid plates; Q-middle of the right upper horn; R-middle of the left upper horn; S-middle of the right lower horn; T-middle of the left lower horn; α-thyroid angle prior to cricothyroid joint dissection and thyroid cartilage separation from other laryngeal parts