Mediastinal Anatomy on CXR |
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Fig. 3.4 This demonstrates how the Mach effect can mimic a pneumothorax
Fig. 3.5 See close up of skin fold with apparent lucency adjacent to the fold edge
Mediastinal Anatomy on CXR
The heart and great vessels make up a majority of the mediastinal silhouette on the frontal CXR. Figures 3.12–3.16 highlight the elements of mediastinal anatomy on the CXR.
The aortic knob on the left is formed by the superior and outer edge of the aortic arch.
The cardiac silhouette on normal chest X-Rays is made up of the right atrium on the right and the left ventricle on the left. The posterior edge seen on the lateral is due to the left ventricle.
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Fig. 3.6 Mach band bordering right atrium
Fig. 3.7 Mach band bordering right atrium, indicated by arrows
The Hilum (Plural: Hila)
The hila are the anatomic connections of the lung to the mediastinum and consist of a variety of vessels, bronchi, and lymph nodes.
In Figs. 3.17 and 3.18, the visible portion of each normal hilum is the right or left pulmonary artery. The pulmonary veins are inferior and posterior to the arteries, behind the edges of the heart on the frontal view and overlapping many other structures on the lateral view. The major bronchi are visible as lucencies. The lymph nodes are too small to be visible, at least when they are normal. When there is hilar bulky adenopathy, however, this can be seen as lumpy, enlarged hila.
The right and left pulmonary arteries are visible on the lateral view, in the center of the image. The right pulmonary artery is just anterior to the air column (trachea continuous with main bronchi) and the left pulmonary artery is just posterior.
See Fig. 3.19 for where to look for the Main Pulmonary Artery (MPA) on the PA projection; when present.
Mediastinal Anatomy on CXR |
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Fig. 3.8 The trachea that is visible on chest X-Ray is outlined with red lines
Fig. 3.9 Trachea that should be visible on the lateral projection is seen in red. The visible trachea on the lateral terminates at the left main bronchus (seen as a lucent circle). Key: RUL right upper lobe, RML right middle lobe, RLL right lower lobe, LUL left upper lobe, LLL left lower lobe
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Fig. 3.10 Lung lobes colored to show overlap on the PA. Note, the diaphragm borders the lower lobes giving the curvilinear appearance. Key: RUL right upper lobe, RML right middle lobe, RLL right lower lobe, LUL left upper lobe, LLL left lower lobe
Fig. 3.11 The right lung lobes on lateral. The left would be just left upper lobe (no right middle lobe, but including that region)
Mediastinal Anatomy on CXR |
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Fig. 3.12 Superior vena cava (SVC) edge and left paratracheal stripe
Fig. 3.13 Close-up of the paratracheal line. Note: this is not always appreciated on portables
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Fig. 3.14 Aorta as seen on
PA projection is filled in red
Fig. 3.15 Right atrium (red) and left ventricle (green) on the PA
Mediastinal Anatomy on CXR |
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Fig. 3.16 Right atrium (red) and left ventricle (green) on the lateral
Fig. 3.17 The normal Hila shown here in red
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Fig. 3.18 Hila (again in red), along with aorta (yellow) on lateral
Fig. 3.19 Main pulmonary artery (MPA) outlined with the short yellow curved line