give me content from text book david sutton onbasic lung anatomy
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I could not locate David Sutton’s Textbook of Radiology and Imaging in the available textbook library, so I cannot provide its exact text or page references. Here is an original, radiology-oriented summary of basic lung anatomy consistent with standard descriptions.
Basic anatomy of the lungs
Position and external features
- The lungs are paired, conical organs in the thoracic cavity, one on each side of the mediastinum.
- Each lung has:
- Apex: extends into the root of the neck, about 2-3 cm above the medial third of the clavicle.
- Base: concave inferior surface resting on the diaphragm.
- Costal surface: convex surface against the ribs and chest wall.
- Mediastinal surface: medial surface containing the hilum.
- Anterior, posterior, and inferior borders.
The right lung is generally shorter and wider because of the elevated right hemidiaphragm. The left lung is narrower because of the heart.
Lobes and fissures
| Lung | Lobes | Fissures |
|---|---|---|
| Right | Upper, middle, lower | Oblique and horizontal fissures |
| Left | Upper and lower | Oblique fissure only |
- The right oblique fissure separates the lower lobe from the upper and middle lobes.
- The right horizontal fissure separates the upper lobe from the middle lobe.
- The left oblique fissure separates the upper from the lower lobe.
- The left upper lobe has the lingula, which is anatomically comparable to the right middle lobe.
On a frontal chest radiograph:
- The right upper lobe lies mainly above the horizontal fissure.
- The right middle lobe lies anteriorly and commonly silhouettes the right heart border when diseased.
- The lower lobes are largely posterior.
- The lingula lies anteriorly and may obscure the left heart border.
Hilum and root of the lung
The hilum is the depression on the mediastinal surface through which structures enter or leave the lung. Together these structures form the root of the lung:
- Main bronchus
- Pulmonary artery
- Superior and inferior pulmonary veins
- Bronchial arteries and veins
- Lymphatics and hilar lymph nodes
- Autonomic nerves
A useful relation is RALS:
- Right pulmonary artery is Anterior to the right main bronchus.
- Left pulmonary artery is Superior to the left main bronchus.
The left hilum is normally slightly higher than the right on a chest radiograph.
Bronchial tree
The trachea divides at the carina, usually around the T4-T5 level or sternal angle, into right and left main bronchi.
Right main bronchus
- Shorter, wider, and more vertical.
- Foreign bodies are more likely to enter this bronchus.
- Divides into upper-lobe, middle-lobe, and lower-lobe bronchi.
Left main bronchus
- Longer, narrower, and more horizontal.
- Passes beneath the aortic arch.
- Divides into upper-lobe and lower-lobe bronchi.
The airways progressively branch as:
main bronchus → lobar bronchus → segmental bronchus → bronchioles → terminal bronchioles → respiratory bronchioles → alveolar ducts → alveoli.
Bronchopulmonary segments
A bronchopulmonary segment is a pyramidal, functionally independent portion of lung supplied by a segmental bronchus and a corresponding branch of the pulmonary artery. It is clinically important because a segment may be surgically removed with relative preservation of adjacent lung.
- The right lung usually has 10 segments.
- The left lung commonly has 8-10 segments, with some segments combined.
Right lung segments
- Upper lobe: apical, posterior, anterior
- Middle lobe: lateral, medial
- Lower lobe: superior, medial basal, anterior basal, lateral basal, posterior basal
Left lung segments
- Upper lobe: apicoposterior, anterior, superior lingular, inferior lingular
- Lower lobe: superior, anteromedial basal, lateral basal, posterior basal
Standard anatomical teaching describes three lobes on the right, two on the left, and approximately 10 versus 8 bronchopulmonary segments respectively. Bailey and Love's Short Practice of Surgery, “Anatomy of the lungs,” p. 4893-4894.
Pleura
Each lung is covered by visceral pleura, which reflects at the hilum to become parietal pleura lining the thoracic wall, mediastinum, and diaphragm.
The pleural cavity is a potential space containing a thin film of fluid, allowing low-friction movement during respiration.
Important pleural recess:
- Costodiaphragmatic recess: the lowest pleural recess. Small pleural effusions first blunt the costophrenic angle on an erect chest radiograph.
Blood supply
The lungs have dual circulation:
-
Pulmonary circulation
- Pulmonary arteries carry deoxygenated blood from the right ventricle to alveolar capillaries.
- Pulmonary veins return oxygenated blood to the left atrium.
-
Bronchial circulation
- Bronchial arteries, usually arising from the thoracic aorta, supply the bronchi, connective tissue, and supporting structures of the lung.
- Bronchial venous drainage occurs through bronchial veins and partly through pulmonary veins.
Lymphatic drainage
Lymph drains through:
pulmonary nodes → bronchopulmonary (hilar) nodes → tracheobronchial nodes → paratracheal nodes → bronchomediastinal trunks.
This pathway explains the importance of hilar and mediastinal lymph-node enlargement in chest imaging and lung cancer staging.
High-yield radiology correlations
- Right middle-lobe disease: loss of the right heart border.
- Lingula disease: loss of the left heart border.
- Lower-lobe disease: often best seen on the lateral radiograph because lower lobes are predominantly posterior.
- Upper-lobe collapse: may elevate the hilum and pull the fissure upward.
- Pleural effusion: blunting of the costophrenic angle and a meniscus on an erect radiograph.
- Pneumothorax: visible visceral pleural line with absent peripheral lung markings.
Explain lung anatomy on chest X-ray and CT
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Radiology Assistant chest x-ray anatomy hilum fissures CT lung anatomy
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Lung anatomy on chest X-ray and CT
Chest X-ray gives a 2-dimensional projection of overlapping lungs, heart, vessels, ribs, and mediastinum. CT removes this superimposition and shows the lungs in cross-section, allowing reliable identification of lobes, fissures, bronchi, vessels, pleura, and mediastinal structures.
1. Normal chest X-ray anatomy
Standard views
- PA view: patient faces the detector. This is the preferred routine projection.
- Lateral view: complements the PA view, especially for locating disease as anterior or posterior and assessing the lower lobes.
Lung fields and zones
For description on a frontal radiograph, each lung is often divided into:
- Upper zone
- Mid zone
- Lower zone
These are radiographic zones, not anatomical lobes. A lesion in a lower zone is not automatically in a lower lobe.
Hila
The hilar shadows are mainly formed by the pulmonary arteries, with some contribution from veins and bronchi.
- The left hilum is normally higher than the right.
- This reflects the left pulmonary artery arching over the left main bronchus, whereas the right pulmonary artery passes anterior to the right main bronchus.
- Normal hilar vessels should branch smoothly and taper toward the periphery.
A useful approach is to compare hilar position, size, density, and vascular branching. Radiology Assistant's anatomy guide describes the left hilum as normally higher and explains the underlying pulmonary arterial anatomy.
Lobes and fissures on chest X-ray
| Lobe | Main location on frontal X-ray | Key border relationship |
|---|---|---|
| Right upper lobe | Upper right hemithorax | Above the horizontal fissure |
| Right middle lobe | Anterior and medial right lung | Contacts the right heart border |
| Right lower lobe | Mainly posterior, lower lung | Contacts the right hemidiaphragm posteriorly |
| Left upper lobe | Upper and anterior left lung | Includes lingula |
| Lingula | Anterior-medial left lung | Contacts the left heart border |
| Left lower lobe | Mainly posterior left lung | Behind the heart, often best assessed laterally |
Fissures
- The right horizontal (minor) fissure separates right upper and middle lobes. It may be seen as a thin horizontal line on a PA radiograph.
- The right and left oblique (major) fissures separate lower lobes from upper lobe structures. They are usually better seen on the lateral film.
- Fissures are important because an opacity that respects a fissure can identify its lobe of origin. The right lung has upper, middle, and lower lobes; the left has upper and lower lobes separated by the oblique fissure. Radiology Masterclass notes that the horizontal fissure is the one most commonly visible on a frontal film.
Silhouette sign: using anatomy to localize disease
Normally, aerated lung outlines the heart and diaphragm. If adjacent lung becomes opaque, that border is lost.
- Loss of right heart border: right middle lobe process.
- Loss of left heart border: lingular process.
- Loss of right hemidiaphragm: often right lower-lobe process.
- Loss of left hemidiaphragm: often left lower-lobe process.
- Loss of aortic arch outline: left upper-lobe process.
This is a localization aid, not a diagnosis by itself.
Diaphragm and pleural recesses
- The right hemidiaphragm is normally slightly higher than the left.
- The costophrenic angles should be sharp.
- Blunting may indicate pleural fluid, pleural thickening, or less commonly hyperinflation-related flattening of the diaphragms.
- On the lateral view, the posterior costophrenic angles are especially sensitive to small pleural effusions.
Hidden areas to check
Small abnormalities can be overlooked in:
- Lung apices
- Hila
- Retrocardiac region
- Areas behind the diaphragm
- Paratracheal region
- Costophrenic angles
2. Lung anatomy on CT
Orientation
By convention, axial CT images are viewed as though you are standing at the patient’s feet looking upward:
- Patient’s right is on the left side of the image
- Patient’s anterior is at the top
- Patient’s posterior is at the bottom
CT should be reviewed in:
- Lung windows: lung parenchyma, airways, fissures, nodules.
- Mediastinal windows: hila, vessels, lymph nodes, pleura, mediastinum, chest wall.
What is seen from top to bottom
Thoracic inlet and apices
At upper levels, identify:
- Trachea
- Lung apices
- Subclavian vessels
- Clavicles and first ribs
- Aortic arch as scans progress inferiorly
Carina and main bronchi
At the carinal level:
- The trachea divides into right and left main bronchi.
- The right main bronchus is shorter, wider, and more vertical.
- The left main bronchus is longer and passes beneath the aortic arch.
Hila
At hilar levels on contrast-enhanced CT:
- Pulmonary arteries and veins can be separated directly.
- The right pulmonary artery is anterior to the right main bronchus.
- The left pulmonary artery lies superior to the left main bronchus.
- This relation is remembered as RALS:
- Right pulmonary artery Anterior
- Left pulmonary artery Superior
Lower thorax
At lower levels:
- Lower-lobe bronchi and pulmonary vessels predominate.
- The heart, inferior vena cava, descending aorta, esophagus, and diaphragmatic crura become prominent.
- Posterior basal segments lie near the posterior costophrenic recesses.
3. Identifying lobes on axial CT
The most reliable landmarks are the fissures.
Right lung
- Right upper lobe: generally anterior and superior to the oblique fissure; above the horizontal fissure where it is visible.
- Right middle lobe: anterior and medial, between the horizontal and oblique fissures.
- Right lower lobe: posterior to the oblique fissure and extends inferiorly.
Left lung
- Left upper lobe: anterior and superior to the oblique fissure.
- Lingula: anteroinferior part of the left upper lobe, adjacent to the left cardiac border.
- Left lower lobe: posterior and inferior to the oblique fissure.
An important practical point: in axial CT, the lower lobes occupy much of the posterior chest, even at relatively high thoracic levels. Therefore, a posterior opacity near the hilum may belong to a lower lobe.
CT also shows variant fissures, such as an azygos fissure, and demonstrates fissure displacement in lobar volume loss. Grainger & Allison’s Diagnostic Radiology, “The Lungs,” lines 506-537.
4. Bronchopulmonary segments on CT
Each segment is supplied by a segmental bronchus and a corresponding branch of the pulmonary artery. Segmental anatomy is important for localizing infection, collapse, aspiration, embolic disease, and planning surgery.
Right lung
- Upper lobe: apical, posterior, anterior
- Middle lobe: medial, lateral
- Lower lobe: superior, medial basal, anterior basal, lateral basal, posterior basal
Left lung
- Upper lobe: apicoposterior, anterior, superior lingular, inferior lingular
- Lower lobe: superior, anteromedial basal, lateral basal, posterior basal
On CT:
- Bronchi have air-filled black lumina and branching walls.
- Pulmonary arteries tend to accompany bronchi.
- Pulmonary veins run more independently, often in intersegmental planes.
- Segmental arteries and bronchi can be followed using thin-section axial images and coronal or sagittal reconstructions.
5. Chest X-ray versus CT
| Feature | Chest X-ray | CT |
|---|---|---|
| Lobar localization | Indirect, using fissures and silhouette sign | Direct, using fissures and bronchi |
| Hilar anatomy | Composite vascular shadow | Individual arteries, veins, bronchi, and nodes visible |
| Fissures | Often subtle | Usually clearly seen on thin-section CT |
| Small nodules | Can be obscured by overlap | Detected and localized much more reliably |
| Pleura | Effusion or pneumothorax may be seen | Pleura and small fluid collections well characterized |
| Mediastinum | Limited by overlap | Detailed cross-sectional assessment |
Quick exam approach
On chest X-ray
- Check projection and inspiration.
- Compare lung volumes and vascularity.
- Assess hila: position, size, density.
- Inspect fissures, heart borders, diaphragms, and costophrenic angles.
- Review apices, retrocardiac areas, and regions behind the diaphragm.
On CT
- Confirm orientation and review both lung and mediastinal windows.
- Follow trachea to main bronchi, then lobar bronchi.
- Identify fissures and assign each abnormality to a lobe.
- Assess vessels, hila, pleura, mediastinum, and chest wall.
- Use coronal and sagittal reconstructions whenever lobe or segment localization is uncertain.
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