Hilum vs Root of Lung: Key Differences Every Anatomy Student Must Know
The hilum is the doorway on the medial lung surface where bronchi, vessels, and nerves enter and exit. The root of lung is the entire bundle of those same structures plus surrounding connective tissue and pleura that actually anchor the lung to the mediastinum.
Students swap the terms because both sit in the same spot on a chest CT. In the OR, surgeons say “hilar dissection” when freeing the hilum but “divide the root” when removing the whole lung. Same place, two jobs—easy to muddle.
Key Differences
Hilum = slit-like opening on lung’s medial face. Root of lung = full cable-tie of bronchus, vessels, lymphatics, nerves, and pleura that passes through the hilum. One is the doorway; the other is what walks through it.
Which One Should You Choose?
Use “hilum” when describing surface anatomy on imaging or dissection. Use “root” when discussing surgical resection or ligament attachments. Mixing them costs marks in OSCEs and confounds the scrub nurse.
Can a lung have more than one hilum?
No. Each lung has a single hilum on its mediastinal surface; accessory fissures don’t create extra hila.
Is the pulmonary ligament part of the root?
Yes. The ligament is the inferior fold of pleura that extends from the root and anchors the lung to the mediastinum.
Why does the left hilum sit higher than the right?
The heart pushes the left hilum superiorly, while the liver keeps the right hilum lower—classic radiology landmark.