During a thoracotomy, the surgeon inadvertently cuts a structure running vertically in the posterior mediastinum just to the right of the thoracic duct. This structure most likely is the:

• A Azygos vein ✓
• B Right phrenic nerve
• C Hemi-azygos vein
• D Right vagus nerve

Explanation

The thoracic duct ascends through the posterior mediastinum between the aorta (on its left) and the azygos vein (on its right). The azygos vein runs vertically along the right side of the vertebral column, arching anteriorly at T4 to drain into the superior vena cava. Injury to the azygos vein during thoracotomy or esophagectomy can cause significant hemorrhage.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.