Sternal angle IT4 ①向后平对第4 T9 胸椎下缘; 12
①The lower border of the 4th thoracic vertebra ①向后平对第4 胸椎下缘；
Pulmonary Arteries and Veins ②气管分为左、右主支气管的水 平,即气管权水平;
②The level where the trachea divides into the right and left principal (main) bronchi. ②气管分为左、右主支气管的水 平，即气管杈水平；
Bronchial arteries ③平左主支气管 与食管交叉处 即食管的第2狭窄 处 Esophagus Trachea(pulled to left by hook] Superior left bronchial artery 3rd right posterior intercostal artery Right bronchial artery Aorta(pulled aside by hook] Right main (primary Inferior left bronchial artery Left main (primary) bronchus [pulled to right by hook) Esophageal branch
③ The second constriction of the esophagus ③平左主支气管 与食管交叉处， 即食管的第2狭窄 处；
④平主动脉弓的起、 止处;
④ The origin and end of the aortic arch ④平主动脉弓的起、 止处；
⑤动脉韧带连与左肺动脉 与主动脉弓之处;
⑤The ligamentum arteriosum joins the left pulmonary artery to the aortic arch ⑤动脉韧带连与左肺动脉 与主动脉弓之处；