Although the thoracic cavity houses two vital organs, the heart and lungs, the anatomic structures of the chest wall are important sources of the information concerning cardiac and pulmonary function, skeletal formation. The chest is inspected for size, shape, symmetry, movement and the presence of the bony landmarks formed by the ribs and sternum.
Important landmarks of the Chest
The doctor must become familiar with locating and properly numbering each rib, because they are geographic landmarks for palpating, percussing, and asucultatin underlying organs. Normally all the ribs can be counted by palpating inferiorly from the second rib. The tip of the eleventh rib can be felt laterally and the tip of the twelfth rib can be felt posteriorly. Other helpful landmarks include the nipples, which are usually located between the fourth and fifth ribs or at the fourth intercostal space and posteriorly, the tip of the scapula, which is located at the level of the eighth rib or intercostal space. In children with the thin chest walls, correctly locating the ribs is little difficult.
The thoracic cavity is also divided into segments by drawing imaginary lines on the chest and back: the anterior, lateral, and posterior divisions. The doctor should become familiar with each imaginary landmark, as well as with the rib number and corresponding intercostal space.
The size of the chest is measured by placing the tape around the rib cage at the nipple line. For the greatest accuracy at least two measurements should be taken, one during inspiration and the other during expiration, and the average recorded. The chest size is important mainly in comparison to its relationship with the head circumference. Marked disproportions are always recorded, because most are caused by abnormal head growth, although some may be the result of altered chest shape, such as barrel chest or pigeon chest.
As the child grows, the chest normally increases in the transverse direction, causing the antero-posterior diameter to be less than the lateral diameter. In an older child the characteristic barrel shape of an infant’s chest is a significant sign of chronic obstructive lung disease, such as asthma or cystic fibrosis. Other variations in shape that are usually variants of the normal configuration are pigeon breast, or pectus carinatum, in which the sternum protrudes outward, increasing the anterior-posterior diameter, and funnel chest, or pectus excavatum. In which the lower portion of the sternum is depressed. A severe depression may impair cardiac function, but in general neither condition causes pathologic dysfunction. However, these conditions often cause parents and children concern regarding acceptable physical appearance.
The doctor also notes the angle made by the lower costal margin and the sternum, which ordinarily is about 45 degrees. A larger angle is characteristic of lung diseases that also cause a barrel shape of the chest. A smaller angle may be a sign of malnutrition. As the rib cage is inspected, the junction of the ribs to the costal cartilage (costochondral junction) and sternum is noted. Normally the points of attachment are fairly smooth. Swellings or bunt knobs along either side of the sternum are known as the rachitic rosary and may indicate vitamin D deficiency. Another variation in shape that may either be normal or may suggest rickets (vitamin D deficiency) is Harrison’s groove, which appears as a depression or horizontal groove where the diaphragm leaves the chest wall. Usually marked flaring of the rib cage below the groove is an abnormal finding.
Body symmetry is always an important notation during inspection. Asymmetry in the chest may indicate serious underlying problems, such as cardiac enlargement (bulging on the left side of rib cage) or pulmonary dysfunction. However, asymmetry is most often a sign of scoliosis, lateral curvature of the spine. Asymmetry warrants further medical investigation.
Movement of the chest wall is noted. It should be symmetric bilaterally and coordinated with breathing. During inspiration the chest rises and expands, the diaphragm descends, and the costal angle increase. During expiration the chest falls and decreases in size, the diaphragm rises, and the costal angel narrows. In children under 6 or 7 years of age, respiratory movement is principally abdominal or diaphragmatic. In older children, particularly females, respirations are chiefly thoracic, in either type, the chest and abdomen should rise and fall together.
Any asymmetry of movement is an important pathologic sign and is reported. Decreased movement on one side of the chest may indicate pneumonia, pneumothorax, atelectasis, or an obstructive foreign body. Marked retraction of muscles either between the ribs (intercostals), above the sternum (suprasternal), or above the clavicles (supraclavicular) is always noted, because it is a sign of respiratory difficulty.
The newborns’ chest is almost circular because the antero-posterior and lateral diameters are equal. The ribs are very flexible and slight intercostals retractions are normally seen on inspiration. The xyphoid process is commonly visible as a small protrusion at the end of the sternum. The sternum is generally raised and slightly curved.