Which of the following structures is located in the superior mediastinum?

Explanation

## Superior Mediastinum — Anatomical Boundaries and Contents ### Boundaries The superior mediastinum lies above the sternal angle (angle of Louis), which corresponds to the intervertebral disc between T4 and T5 vertebrae. ### Key Contents of Superior Mediastinum **Key Point:** The superior mediastinum contains the **arch of aorta** and its three branches (brachiocephalic, left common carotid, and left subclavian arteries), along with the **superior vena cava**, **brachiocephalic veins**, and the **trachea**. ### Contents by Mediastinal Division | Structure | Superior Mediastinum | Inferior Mediastinum | |-----------|----------------------|----------------------| | Arch of aorta | ✓ | — | | Brachiocephalic vessels | ✓ | — | | Pulmonary arteries/veins | — | ✓ (in hilum) | | Inferior vena cava | — | ✓ | | Esophagus | ✓ (upper part) | ✓ (lower part) | | Thoracic duct | ✓ (upper part) | ✓ (lower part) | | Heart and pericardium | — | ✓ (middle mediastinum) | ### Clinical Correlation **Clinical Pearl:** The arch of aorta is the key landmark of the superior mediastinum. Pathology affecting the arch (aneurysm, dissection, atherosclerosis) presents with superior mediastinal signs. **High-Yield:** Remember that the **inferior mediastinum** is subdivided into: - **Anterior mediastinum** — fat, connective tissue, lymph nodes - **Middle mediastinum** — heart, great vessels, main bronchi, nerves - **Posterior mediastinum** — esophagus, thoracic aorta, azygos system, thoracic duct