Fig. 1

Anatomy of the thoracic inlet. The trachea is commonly located anterior and right lateral to the esophagus. The aortic arch typically gives rise to three main branches: the brachiocephalic artery (also known as the innominate artery or brachiocephalic trunk) which divides into the right common carotid artery and right subclavian, the left common carotid artery, and the left subclavian artery. The subclavian veins join the internal jugular veins to form the brachiocephalic veins (also known as innominate veins), which empty into the superior vena cava (SVC). The brachial plexus is comprised of nerve roots from cervical level 5 to thoracic level 1 and provides motor and sensory innervation to the shoulder and arm [1]. The phrenic nerve arises from cervical levels 3–5, running along the anterior surface of the anterior scalene muscle in the neck and enter the thorax posterior to the subclavian vein, providing innervation for the diaphragm. The bilateral vagus nerves are rarely directly discernible, even with high-resolution imaging. Their location, however, may be inferred by recognizing anatomic landmarks of their expected course and should be kept in mind during interpretation [1]. The thyroid isthmus lies just above the level of the thoracic inlet in the midline. The right and left lobes of the thyroid may extend inferiorly through the thoracic inlet into the mediastinum/substernal space [2]