1. Ben Barnard Department of Radiology Kimberley Hospital
Lung Anatomy
Ben Barnard
Department of Radiology
Kimberley Hospital

2. Outline Basic morphology Fissures Bronchopulmonary segments
Pulmonary vessels
Bronchial vessels
Lymphatics
Lung roots
Pleura
Radiological features

3. Basic morphology Surfaces Right lung Left lung Costal Mediastinal
Apical
Diaphragmatic
Right lung
Three lobes
Left lung
Two lobes
Lingula of the upper lobe corresponds to right middle lobe

4. Lobules One terminal bronchiole with lung tissue forms an acinus
Acinus with vessels, lymphatics and nerves form the primary lobule
Three to five primary lobules form a secondary lobule

7. Interlobar fissures Oblique (major) fissure
Extends from T4/T5 posteriorly to the diaphragm antero-inferiorly
Left major fissure is more vertically orientated
Undulating in course
Medial aspect passes through the hilum
Lateral aspect is anterior to the medial aspect at the level of the hila and below
Above the hila, the lateral aspect is more posterior

9. Interlobar fissures Transverse (minor) fissure
Separates upper and middle lobes of the right lung
Runs horizontally from the hilum to the anterior and lateral surfaces of the right lung
Level of the fourth costal cartilage
Posterior limit is the right oblique fissure, which it meets at the level of the 6th rib in the midaxillary line
Anatomically complete in only 33% of people and absent in 10%

10. Accessory fissures Azygos fissure Superior accessory fissure
Downward invagination of the azygos vein through the apical portion of the right upper lobe
Four pleural layers – two visceral and two parietal
Superior accessory fissure
Separates the apical segment of the right lower lobe from the other basal segments
Lies parallel and inferiorly to the transverse fissure
Passes posteriorly from the right oblique fissure to the posterior surface of the lung
Inferior accessory fissure
Separates the medial basal from the other right lower lobe segments
Also called Twining’s line
Left transverse fissure
Separates the lingula from the rest of the left upper lobe segments
Rarely seen

11. Azygos Fissure

12. Bronchopulmonary segments
Each lobe is divided into several bronchopulmonary segments
Each is supplied by
Segmental bronchus
Segmental artery
Segmental vein
Each segment is named for its supplying bronchus
Anatomy of the segmental bronchi is subject to variations – the most common being the origin of the apical segment bronchi from the trachea

15. Collateral air drift
Very little connection between segments except via
Pores of Kohn
Openings in alveolar walls
Connect adjacent alveolar lumens
Canals of Lambert
Connections between terminal bronchioles and adjacent alveoli
Allow gas and fluid transfer between segments but not between lobes
Ventilation of a segment is thus possible when its segmental bronchus is occluded = collateral air drift

16. Pulmonary arteries
Pulmonary trunk leaves pericardium and bifurcates in the concavity of the aortic arch anterior to the left main bronchus

17. Right Pulmonary Artery
Longer than the left
Passes across the midline below the carina and comes to lie anterior to the right main bronchus
It bifurcates while still in the hilum of the right lung
An artery to the right upper lobe passes anterior to the right upper lobe bronchus
Interlobar artery to the right middle and lower lobes passes with the bronchus intermedius

18. Left Pulmonary Artery
Left pulmonary artery spirals over the superior aspect of the left main bronchus to reach its posterior surface
It is attached to the concavity of the aortic arch by the ligamentum arteriosum
Pulmonary arteries further subdivide into segmental arteries that travel with the segmental bronchi, mostly on their posterolateral surfaces
Pulmonary arteries supply only the alveoli

19. Pulmonary veins These do not follow the bronchial pattern
Tend to run in intersegmental septa
Two veins pass to each hilum from lung tissue above and below each oblique fissure
They enter the mediastinum slightly below and anterior to the pulmonary arteries
The lobar veins on the right may remain separate – such that three veins leave the right lung and enter the left atrium
The left pulmonary veins may unite and enter the left atrium as a single vessel

20. Bronchial arteries
Supply the bronchi, visceral pleura and connective tissues of the lungs
Arise from the thoracic aorta at the T5 or T6 level
Usually one right and two left bronchial arteries
Arise at the upper border of T5
When a second bronchial artery occurs on the right, it often arises from the third intercostal artery
Bronchial arteries may also arise from the subclavian or internal mammary arteries
Tissues supplied by the bronchial arteries drain to the pulmonary or bronchial veins

22. Bronchial veins Form two distinct systems Deep veins Superficial veins
Form a network around the pulmonary interstitium
Communicate freely with pulmonary veins
Form a bronchial venous trunk that drains to the pulmonary system
Superficial veins
Drain to the azygos vein on the right and the accessory hemiazygos vein on the left

23. Lymphatics
Mediastinal lymph nodes that drain the lung are named according to position
Pulmonary nodes
Bronchopulmonary nodes
Carinal nodes
Tracheobronchial nodes
Right and left paratracheal nodes

25. Lymphatics
Lymph vessels of the lungs are in superficial and deep plexuses
Superficial plexus beneath the pleura drains around the surface of the lungs and the margins of the fissures to converge at the hila and bronchopulmonary nodes
Deep channels drain with the pulmonary vessels towards the hila
Few connections between superficial and deep plexuses except at the hila
Bronchopulmonary nodes drain to tracheobronchial nodes and paratracheal nodes and then into the bronchomediastinal trunks

26. Lung roots
Roots of the lungs are formed by structures that enter and emerge at the hila
Lie at T5-T7 level
Right lung root lies below the arch of the azygos vein and posterior to the SVC and right atrium
Left lung root lies below the arch of the aorta and anterior to the descending aorta

27. Pleura Serous membrane that
Covers the lung (visceral pleura)
Lines the thoracic cavity (parietal pleura)
Both layers are continuous with each other anterior and posterior to the lung root
Below the hilum they hang down in a loose fold called the pulmonary ligament
This allows descent of the lung root in respiration and distension of the pulmonary veins

28. Pleura
Visceral pleura extends into the interlobar and accessory fissures
At rest the parietal pleura extends deeper into the costophrenic and costomediastinal recesses than the lungs and visceral pleura
Parietal pleura is supplied by the systemic vessels
Visceral pleura is supplied by the bronchial and pulmonary circulation

29. Imaging of the Lungs

30. CXR PA

31. CXR L Lat

32. Pulmonary angiography

33. Bronchial angiography

34. CT

35. HRCT

36. Dual-Energy CT

37. MRI

38. MRA/MRV & Dynamic Airway Imaging

39. Isotope V/Q Scanning

40. SPECT

41. PET-CT

42. What’s missing?

43. Thank you

44. References
Netter, F.H. (2011). Atlas of Human Anatomy, 5th ed. Philadelphia: Saunders Elsevier
Ryan, S., McNicholas, M., Eustace, S. (2011). Anatomy for diagnostic imaging, 3rd ed. London: Saunders Elsevier
Butler, P., Mitchell, A.W.M., Ellis, H. (1999). Applied Radiological Anatomy. Cambridge: Cambridge University Press
Karcaaltincaba M, Aktas A. Dual-energy CT revisited with multidetector CT: review of principles and clinical applications. Diagn Interv Radiol 2011; 17: