Lungs vs. Mediastinum: Anatomic Relationship

The lungs occupy the lateral thoracic cavities (right and left pleural cavities). The mediastinum is the central compartment between the lungs.

Mediastinal Contents

• Heart (in middle mediastinum, pericardial sac)
• Great vessels: Ascending/arch/descending aorta, SVC, IVC, pulmonary trunk/arteries/veins
• Trachea & main bronchi
• Esophagus (posterior)
• Thymus (anterior, prominent in children, involutes)
• Thoracic duct (lymphatic drainage)
• Vagus, phrenic, recurrent laryngeal nerves
• Lymph nodes (stations for lung cancer staging)

Mediastinal Divisions

• Superior: Above thoracic inlet plane
• Anterior: Thymus, fat, lymph nodes
• Middle: Heart, great vessels, tracheal bifurcation
• Posterior: Esophagus, thoracic duct, descending aorta, azygos, sympathetic chain

The lungs and mediastinum are adjacent but distinct compartments. Pathology in one often affects the other (e.g., lung cancer → mediastinal nodes; mediastinal mass → tracheal/bronchial compression).