GLOSSARY

The hilum of the lung is a depressed area on the mediastinal (medial) surface of each lung where the structures of the root of the lung enter and leave, connecting the lung to the heart and trachea.

Contents of the Lung Root

• Main bronchus.
• Pulmonary artery (oxygen-poor blood).
• Two pulmonary veins (oxygen-rich blood).
• Bronchial arteries and veins.
• Pulmonary nerve plexuses (sympathetic and vagal).
• Lymphatic vessels and hilar lymph nodes.

Arrangement of Structures

• Right lung: the bronchus is superior and posterior; the upper lobe bronchus sometimes lies above the artery (the eparterial bronchus).
• Left lung: the pulmonary artery is highest.
• In both: the pulmonary veins lie anterior and inferior.

Covering

At the hilum, the pleura reflects from visceral to parietal, forming below it a fold called the pulmonary ligament.

Clinical Application

• Hilar lymph node enlargement: in sarcoidosis, tuberculosis, lymphoma, and lung cancer; visible on a chest X-ray.
• Surgery: hilar structures must be carefully identified in pneumonectomy and lobectomy.

Relevance to Sport

• Practical example: sarcoidosis with hilar node involvement sometimes presents in young athletes with fatigue, dry cough, and reduced performance and may be mistaken for overtraining.