表 3.
气管软骨环总数和头臂干上方气管软骨环数（个）
Total number of tracheal cartilage rings and the number of tracheal cartilage rings above the brachiocephalic trunk
| Item | Male (n=70) | Female (n=21) | t | P | |||||
| Maximum | Minimum | Mean±SD | Maximum | Minimum | Mean±SD | ||||
| Three cases (2 male and 1 female) where the brachiocephalic trunk and the trachea were not intersected were excluded. | |||||||||
| Total number of tracheal cartilage rings | 19 | 13 | 15.74±1.68 | 18 | 13 | 15.14±1.62 | 1.445 | 0.152 | |
| Number of tracheal cartilage rings above the brachiocephalic trunk | 9 | 3 | 6.54±1.58 | 10 | 4 | 7.35±1.73 | 1.966 | 0.053 | |