Thoracic trachea

The thoracic trachea is the continuation of the trachea inferior to the superior thoracic inlet through the superior mediastinum. Usually, it extends for 5-8cm behind the manubrium sternii and ends with the bifurcation of the trachea into the two main stem bronchi. Posteriorly along its length is the oesophagus. Anterosuperiorly are the inferior thyroid veins approximately in the median plane. Anterior to these are the sternohyoid and sternothyroid muscles beneath the manubrium sternii.

Anteriorly in the middle portion of the thoracic trachea, the right common carotid trunk meets the left common carotid artery as they pass medially to the arch of the aorta. The arch covers the anterior and left lateral borders of the inferior part of the trachea; the ascending aorta covers the left anterior region of the tracheal bifurcation.

On the right side of the trachea, the parietal pleura of the right lung is closely apposed. Between lung and pleura on the right is the vagus nerve which passes medially after it has crossed the right subclavian artery to reach this site. It gives off many anterolaterally-running cardiac nerves near the tracheal bifurcation. On the left, the common carotid and subclavian arteries separate trachea from pleura. The left recurrent laryngeal nerve hooks under the arch of the aorta to run superiorly between trachea and oesophagus.

At the inferior right lateral margin of the trachea, the azygous vein arches over to join the superior vena cava. The superior vena cava occupies the right anterolateral section of the trachea from where it is produced by the union of the two brachiocephalic veins. The veins run anterior to the great arteries in front of the trachea. Anterior to both of these structures are, from deep to superficial, the thymus and the manubrium sternii.