**4.1 Structural features and anatomical position of healthy heart**

The structure of a healthy human heart roughly resembles the shape of the heart on a playing card (**Figure 2A**) [3], with around two-thirds of its mass located to the left of the midline [10]. The human heart lies obliquely in the thorax which shields the *Perspective Chapter: Physiology and Pathology of the Cardiovascular System DOI: http://dx.doi.org/10.5772/intechopen.108355*

**Figure 2.** *Healthy heart (A) vs. diseased heart (B) (designed with biorender).*

delicate anatomical structure of the heart. It is positioned roughly on a plane that spans from the right shoulder to the left nipple of the body [10]. Its anterior surface confronts the sternum, whereas its posterior surface confronts the vertebral column. However, the inferior surface of the heart is supported by the superior surface of the diaphragm. The human heart is housed in an enclosed region within the pleural cavities known as the middle mediastinum, which refers to the inner space of the pericardium, the protective sac that covers and cushions the heart as well as keeps the heart separated from other parts of the chest, including the lungs [9]. This pericardium is a serous membrane, which consists of a fibrous thick outer layer (the parietal pericardium) and an inner layer (visceral pericardium) separated by a lubricating substance known as the "serous fluid" (25–35 ml), that aids to "glide" the inner visceral pericardium against the outer parietal one [2, 10]. This pericardium serves to limit the heart's ability to expand excessively.
