The arch of the aorta begins and ends at the transverse plane between the sternal angle anteriorly and vertebral level TIV/V posteriorly. The arch may reach as high as the midlevel of the manubrium of the sternum.
Visualizing the margins of the heart
Surface landmarks can be palpated to visualize the outline of the heart (Fig. 3.109).
The upper limit of the heart reaches as high as the third costal cartilage on the right side of the sternum and the second intercostal space on the left side of the sternum.
The right margin of the heart extends from the right third costal cartilage to near the right sixth costal cartilage.
The left margin of the heart descends laterally from the second intercostal space to the apex located near the midclavicular line in the fifth intercostal space.
The lower margin of the heart extends from the sternal end of the right sixth costal cartilage to the apex in the fifth intercostal space near the midclavicular line.
Where to listen for heart sounds
To listen for valve sounds, position the stethoscope downstream from the flow of blood through the valves (Fig. 3.110).
The tricuspid valve is heard just to the left of the lower part of the sternum near the fifth intercostal space.
The mitral valve is heard over the apex of the heart in the left fifth intercostal space at the midclavicular line.
The pulmonary valve is heard over the medial end of the left second intercostal space.
The aortic valve is heard over the medial end of the right second intercostal space.
Visualizing the pleural cavities and lungs, pleural recesses, and lung lobes and fissures
Palpable surface landmarks can be used to visualize the normal outlines of the pleural cavities and the lungs and to determine the positions of the pulmonary lobes and fissures.
Superiorly, the parietal pleura projects above the first costal cartilage. Anteriorly, the costal pleura approaches the midline posterior to the upper portion of the sternum. Posterior to the lower portion of the sternum, the left parietal pleura does not come as close to the midline as it does on the right side. This is because the heart bulges onto the left side (Fig. 3.111A).
Inferiorly, the pleura reflects onto the diaphragm above the costal margin and courses around the thoracic wall following an VIII, X, XII contour (i.e., rib VIII in the midclavicular line, rib X in the midaxillary line, and vertebra TXII posteriorly).
The lungs do not completely fill the area surrounded by the pleural cavities, particularly anteriorly and inferiorly.
Costomediastinal recesses occur anteriorly, particularly on the left side in relationship to the heart bulge.
Costodiaphragmatic recesses occur inferiorly between the lower lung margin and the lower margin of the pleural cavity.
In quiet respiration, the inferior margin of the lungs travels around the thoracic wall following a VI, VIII, X contour (i.e., rib VI in the midclavicular line, rib VIII in the midaxillary line, and vertebra TX posteriorly).
In the posterior view, the oblique fissure on both sides is located in the midline near the spine of vertebra TIV (Figs. 3.111B and 3.112A). It moves laterally in a downward direction, crossing the fourth and fifth intercostal spaces and reaches rib VI laterally.
In the anterior view, the horizontal fissure on the right side follows the contour of rib IV and its costal cartilage and the oblique fissures on both sides follow the contour of rib VI and its costal cartilage (Fig. 3.112B).
Where to listen for lung sounds
The stethoscope placements for listening for lung sounds are shown in Fig. 3.113.
Fig. 3.1 Thoracic wall and cavity.