All of the following structures are contained within the superior mediastinum EXCEPT:

Explanation

## Mediastinal Divisions and Contents ### Superior Mediastinum (Above Sternal Angle 2) The superior mediastinum extends from the thoracic inlet (T1) superiorly to the sternal angle 2 (approximately T4/T5 vertebral level) inferiorly. **Key Point:** The superior mediastinum contains: - Arch of aorta and its three branches (brachiocephalic, left common carotid, left subclavian) - Superior vena cava (formed by confluence of brachiocephalic veins) - Trachea (upper portion) - Main bronchi (at the bifurcation, T5 level) - Esophagus (upper portion) - Thoracic duct - Vagus and phrenic nerves - Thymus gland ### Inferior Vena Cava (IVC) — Location **High-Yield:** The inferior vena cava is an **abdominal structure**. It: - Begins at the confluence of the common iliac veins at L5 vertebral level - Passes through the caval opening of the diaphragm (at T8 level) - Enters the right atrium of the heart - Does NOT lie within the mediastinum proper — it is retroperitoneal and passes through the diaphragm ### Clinical Pearl: The IVC is sometimes confused with the SVC in mediastinal anatomy, but the IVC is definitively an **abdominal and subdiaphragmatic structure**, not a mediastinal content. **Mnemonic: SMART (Superior Mediastinum Anterior Relationships):** - **S**uperior vena cava - **M**ain bronchi - **A**rch of aorta - **R**ecurrent laryngeal nerve - **T**rachea | Structure | Location | Mediastinal? | |-----------|----------|-------------| | Arch of aorta | Superior mediastinum | Yes | | Superior vena cava | Superior mediastinum | Yes | | Trachea (upper) | Superior mediastinum | Yes | | Main bronchi | At T4/T5 (superior-middle junction) | Yes | | **Inferior vena cava** | **Abdominal/retroperitoneal** | **No** |