The anterior anatomical relationships of the thoracic trachea must also be known. The veins are external and not in direct contact with the trachea. The left innominate vein which runs just over the aortic arch slightly oblique, inferior and to the right converges with the right innominate vein to form the superior vena cava which lies slightly to the right of the trachea. At its base and posteriorly, the superior vena cava receives the large azygos vein which winds around the right inferior aspect of the trachea.

Left innominate vein

Right innominate vein

Superior vena cava

Aortic arch

Innominate artery

Some of the arteries are in direct contact with the trachea.
The aortic arch courses obliquely from right to left across the left anterior aspect of the trachea. In fact, the aortic arch and the trachea are in such close proximity that the latter becomes slightly indented and deviated to the right near the main carina. As it continues its course, the aortic arch winds over the left main stem bronchus and descends against the vertebral column.
The innominate artery arises just in front of the trachea from the convexity of the aortic arch. It ascends obliquely up the anterior right aspect of the trachea. At the base of the neck the innominate artery divides into the right subclavian artery and the right common carotid artery.



The left common carotid artery lies against the left side of the trachea, but as it heads toward the neck, it veers away from the airway.
The left subclavian artery runs oblique, anterior, and outward, and thus is not in direct contact with the thoracic trachea.
The left vagus nerve descends parallel to the left common carotid artery, crosses the left side of the aortic arch, and gives rise to the left recurrent laryngeal nerve which loops around the aortic arch, and then continues its course along the groove formed between the left sides of the trachea and esophagus.
The posterior aspect of the thoracic trachea is closely related to the esophagus which veers progressively leftward into the stomach.

Left common carotid artery

Left subclavian artery

Esophagus