Surface Anatomy

When performing lung ultrasound (LUS), which lobes are we actually scanning? To answer this question, it is important to understand surface anatomy, which is helpful both for physical examination and for LUS.

Please note that surface anatomy listed below is approximate only. Variations exist in both textbooks and in real life. Therefore, use these figures for guidance only and not for definitive diagnostic localization purposes.

Lobes and Fissures

Horizontal fissure divides the right upper lobe (RUL) from the right middle lobe (RML). Oblique fissure divides RML from right lower lobe (RLL) and left upper lobe (LUL) from left lower lobe (LLL).

Zone 1 ~ RUL

Zone 2 ~ RML

Zone 5 ~ LUL

Zone 6 ~ LLL but often obscured by the heart

Anterior Surface Anatomy

Right Lung: Horizontal fissure starts approximately at Rib 4 medially, extending to Rib 5 laterally. Oblique fissure then extends to Rib 6 medially. The lung extends down to Rib 7 laterally.

Left Lung: Oblique fissure starts approximately at Rib 5 laterally, extending to Rib 6 medially. The lung extends down to Rib 7 laterally.

Posterior Surface Anatomy

Left Lung: Oblique fissure starts approximately at the T3 spinous process and extends laterally to Rib 5 to divide the left upper lobe (LUL) from left lower lobe (LLL)

Right Lung: Oblique fissure starts at approximately between T3-T4 spinous processes and extends laterally to Rib 6 to divide between the right upper lobe (RUL) from right lower lobe (RLL).

Only a tiny amount of right middle lobe (RML) is accessible posteriorly.

Lateral Zones

Zone 3 is most often RUL, but can be RML depending on transducer positioning.

Zone 4 should be RLL

Zone 7 is LUL

Zone 8 is LLL

ADVANCED LUS: LUNG SEGMENTS

Ever wonder about what lung segments you might be scanning? But before proceeding, a word of caution: The segments listed below are approximate only. The figures may help guide you better understand locations of pathology. Do NOT use the figures to definitively localize findings.

Anterior Lung Segments

Posterior Lung Segments

Lateral Lung Segments

REFERENCES

Netter, FH (1989). Atlas of Human Anatomy. CIBA-GEIGY Corporation, West Caldwell, NJ.
Lumley, John SP (2008). Surface Anatomy. The Anatomical Basis of Clinical Examination. 4th Ed. Churchill Livingstone, Elsevier, Philadelphia, PA
Smith, Claire F; Dilley, Andrew ;Mitchell Barry S; Drake , Richard L (2018) Gray's Surface Anatomy and Ultrasound. A Foundation for Clinical Practice. Elsevier Limited.