ABSTRACT

This chapter summarizes the applied anatomy of the newborn, emphasizing aspects that are clinically relevant and different to adults. Growth involves changes in size and mass, and includes processes such as cell division, specialization, and apoptosis. At birth, the lungs inflate and, as a result of mechanical effects and oxygen-induced pulmonary vasodilatation, pulmonary vascular resistance falls. The ductus arteriosus starts to close and pulmonary blood flow increases. Cardiovascular adaptation to neonatal life requires the functional closure of three fetal conduits: foramen ovale, ductus arteriosus, and ductus venosus. The neonatal heart is relatively large in relation to the thorax and lungs, and consequently, it occupies a larger proportion of the lung fields on a chest radiograph compared to an adult. At birth, the umbilical vessels constrict rapidly in response to a fall in umbilical cord temperature and hemodynamic changes. The vertebral column in the neonate has no fixed curvatures other than a mild sacral curve.