Locating Findings on the Chest. Describe abnormalities of the chest in two dimensions: along the vertical axis and around the circumference ofthe chest.
To make vertical locations, you must be able to count the ribs and interspaces. The sternal angle, also termed the angle of Louis, is the best guide: place your finger in the hollow curve of the suprasternal notch, then move your finger down about 5 cm to the horizontal bony ridge joining the manubrium to the body of the sternum. Then move your finger laterally and find the adjacent 2nd rib and costal cartilage. From here, using two fingers, you can "walk down the interspaces," one space at a time, on an oblique line illustrated by the red numbers below. Do not try to count interspaces along the lower edge of the sternum; the ribs there are too close together. In a woman, to find the interspaces either displace the breast laterally or palpate a little more medially than illustrated. Avoid pressing too hard on tender breast tissue.
Note that the costal cartilages of the first seven ribs articulate with the sternum; the cartilages of the 8 th, 9th, and 10 th ribs articulate with the costal cartilages just above them. The 11th and 12th ribs, the "floating ribs," have no anterior attachments. The cartilaginous tip of the 11th rib can usually be felt laterally, and the 12th rib may be felt posteriorly. On palpation, costal cartilages and ribs feel identical.
Posteriorly, the 12 th rib is another possible starting point for counting ribs and interspaces: it helps locate findings on the lower posterior chest and provides an option when the anterior approach is unsatisfactory. With the fingers of one hand, press in and up against the lower border of the 12th rib, then "walk up" the interspaces numbered in red below, or follow a more oblique line up and around to the front of the chest.
The inferior tip of the scapula is another useful bony marker—it usually lies at the level of the 7th rib or interspace.
The spinous processes of the vertebrae are also useful anatomic landmarks. When the neck is flexed forward, the most protruding process is usually the vertebra of C7. If two processes are equally prominent, they are C7 and T1. You can often palpate and count the processes below them, especially when the spine is flexed.
To locate findings around the circumference of the chest, use a series of vertical lines, shown in the next three illustrations. The midsternal and vertebral lines are precise; the others are estimated. The midclavicular line drops vertically from the midpoint of the clavicle. To find it, you must identify both ends of the clavicle accurately (see p. 469). The anterior and posterior axillary lines drop vertically from the anterior and posterior axillary folds, the muscle masses that border the axilla. The midaxillary line drops from the apex of the axilla.
Anterior axillary line
Anterior axillary line
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