Anatomy is the study of the structure of an organism and is primarily a morphological science (morphology being the study of structure without regard to function). Function is defined as the activity performed by a body structure. To truly understand the function of the human body, whether normal or abnormal, knowledge of its structure is essential. Physical therapists examine, evaluate, and provide interventions to individuals with various cardiopulmonary impairments. Understanding the cardiopulmonary anatomy allows comprehension of function as well as an appreciation of the relationships between body systems involved with oxygen and nutrient transport. This chapter is not intended to be an exhaustive source of cardiopulmonary anatomy, but it will describe the cardiopulmonary anatomy as it is relevant for the physical therapist. This chapter assumes a basic understanding of anatomical terms and cardiopulmonary anatomy.
The organization of this chapter is based on the functional components of the cardiopulmonary system: ventilation, respiration, and circulation. The physical therapist must understand functional components in order to examine the domains of disablement (ie, pathology, impairment, functional limitation, disability). Often pathological processes alter the anatomy, resulting in impairment of organ function. Impairment of organ function in the cardiopulmonary system impacts the vital processes in the energy transport system. The physical therapist must also understand these structures in order to effectively evaluate, treat, and recognize the various effects of medical and surgical interventions. Finally, the physical therapist must possess the anatomic language to enter into a dialogue regarding disease mechanisms, treatment rationales, and advanced therapeutic concepts. This chapter includes clinical correlates that highlight the importance of cardiopulmonary structure to function and physical therapy evaluation.
EMBRYONIC DEVELOPMENT OF THE CARDIOPULMONARY SYSTEM
This is not intended to be a full review of the embryonic development of the cardiopulmonary system. Its purpose is limited to improving the physical therapist’s understanding of the structural abnormalities underlying various congenital defects, as well as the consequences of premature birth.
The embryonic heart is the first organ to function when the oxygen and nutritional demands of the developing embryo can no longer be met by diffusion from the placenta. The heart begins development on gestational day 19 as a pair of lateral endocardial tubes in the cardiogenic area, in a horseshoe-shaped formation in the buccopharyngeal area, which later forms the pericardial cavity (Fig. 4-1). The lateral endocardial tubes fuse to form the primitive heart tube, which begins beating on day 22 and circulating blood on day 24. The paired dorsal aortae form outflow tracts on the cranial end of the primitive heart tube, and three bilateral pairs of inflow tubes connect with the caudal end to form the vitelline, umbilical, and the common cardinal veins.
Timeline: Formation of the heart. (Reprinted from Larsen WJ. Human Embryology. Copyright 1993, with permission from Elsevier: p. 132.)