Bronchopulmonary Segments of the Left Lung
The left lung has 2 lobes and 10 bronchopulmonary segments.
The left superior lobe is larger than the right because it corresponds to both the right superior lobe and the right middle lobe. Accordingly, the left superior lobar bronchus divides into an upper division (corresponding to right upper lobe) and a lingular division (corresponding to right middle lobe).
Segments by Lobe
Superior (Upper) Lobe — 5 Segments
The left superior lobar bronchus divides into two divisions:
Upper Division — 3 segments (corresponding to right superior lobe):
| No. | Segment | Position |
|---|---|---|
| 1 | Apical | Upper part of upper lobe; projects into root of neck |
| 2 | Posterior | Posterior part of upper lobe |
| 3 | Anterior | Anterior part of upper lobe |
Lingular Division — 2 segments (corresponding to right middle lobe):
| No. | Segment | Position |
|---|---|---|
| 4 | Superior lingular | Upper part of lingula |
| 5 | Inferior lingular | Lower part of lingula; extends below cardiac notch |
The lingula is the tongue-shaped projection of the left upper lobe below the cardiac notch. It corresponds to — but is smaller than — the middle lobe of the right lung.
Inferior (Lower) Lobe — 5 Segments
Supplied by the left inferior lobar bronchus. The arrangement mirrors the right inferior lobe:
| No. | Segment | Position |
|---|---|---|
| 6 | Superior (Apical) | Uppermost, posterior part of lower lobe |
| 7 | Medial basal | Medial basal; usually arises with anterior basal as anteromedial basal |
| 8 | Anterior basal | Anterior basal |
| 9 | Lateral basal | Lateral basal |
| 10 | Posterior basal | Posterior basal |
Note: In the left lung, the medial basal bronchus is usually a small branch of the anterior basal bronchus. They commonly arise from a common stem — the anteromedial basal bronchus. A separate medial basal bronchus is not normally recognised in the left lung.
Summary Table — Left Lung
| Lobe | Division | No. | Segment Name |
|---|---|---|---|
| Superior | Upper | 1 | Apical |
| Superior | Upper | 2 | Posterior |
| Superior | Upper | 3 | Anterior |
| Superior | Lingular | 4 | Superior lingular |
| Superior | Lingular | 5 | Inferior lingular |
| Inferior | — | 6 | Superior (Apical) |
| Inferior | — | 7 | Medial basal |
| Inferior | — | 8 | Anterior basal |
| Inferior | — | 9 | Lateral basal |
| Inferior | — | 10 | Posterior basal |
Right vs Left — Corresponding Segments
| Right Lung | Left Lung |
|---|---|
| Superior lobe: Apical (1) | Upper lobe upper div.: Apical (1) |
| Superior lobe: Posterior (2) | Upper lobe upper div.: Posterior (2) |
| Superior lobe: Anterior (3) | Upper lobe upper div.: Anterior (3) |
| Middle lobe: Lateral (4) | Lingula: Superior lingular (4) |
| Middle lobe: Medial (5) | Lingula: Inferior lingular (5) |
| Lower lobe: Superior (6) | Lower lobe: Superior (6) |
| Lower lobe: Medial basal (7) | Lower lobe: Medial basal (7) — often combined with 8 |
| Lower lobe: Anterior basal (8) | Lower lobe: Anterior basal (8) |
| Lower lobe: Lateral basal (9) | Lower lobe: Lateral basal (9) |
| Lower lobe: Posterior basal (10) | Lower lobe: Posterior basal (10) |