| Region boundaries | Node groups[1,2] | Node group boundaries |
- Superior: Level of lower border of cricoid cartilage
- Anteromedial (neck): Lateral border of sternohyoid, medial border of carotid sheath
- Posterolateral (neck): Anterior border of trapezius
- Anterior (chest): Aortic arch, aortopulmonary window - anterior border of superior vena cava
- Posterior (chest): Esophagus
- Lateral (chest): Pulmonary hila
- Inferior: Diaphragm
| Lower jugular
(AAO-HNS/ASHNS Level 4) | - Superior: Level of lower border of cricoid cartilage
- Anteromedial: Lateral border of sternohyoid
- Posterolateral: Lateral border of sternocleidomastoid
- Inferior: Clavicle
|
Supraclavicular/venous angle: Confluence of internal jugular and subclavian vein
(AAO-HNS/ASHNS Level 5b) | - Superior: Level of lower border of cricoid cartilage
- Anteromedial: Posterior border of sternocleidomastoid
- Posterolateral: Anterior border of trapezius
- Inferior: Clavicle
|
| Internal mammary nodes | - Proximity to internal mammary arteries
|
Upper paratracheal
(IASLC Level 2) | - Superior: Superior border of manubrium, apices of lungs
- Inferior: Intersection of lower border of innominate vein with trachea; superior border of aortic arch
|
Lower paratracheal
(IASLC Level 4) | - Superior: Intersection of lower border of innominate vein with trachea; superior border of aortic arch
- Inferior: Lower border of azygos vein, superior border of left main pulmonary artery
|
Subaortic/aortopulmonary window
(IASLC Level 5) | - Superior: Inferior border of aortic arch
- Inferior: Superior border of left main pulmonary artery
|
Subcarinal
(IASLC Level 7) | - Superior: Carina
- Inferior: Upper border of lower lobe bronchus on the left; lower border of the bronchus intermedius on the right
|
Hilar
(IASLC Level 10) | - Superior: Lower rim of azygos vein on right, upper rim of pulmonary artery on left
- Inferior: Interlobar region bilaterally
|
