The external structure of Heart:
- The heart is situated in the thoracic cavity in between the lungs obliquely towards the left side.
- The anterior end of the heart is broad & it is called as a base. The posterior end is narrow & it is called an apex.
- The heart is covered by the pericardium.
- There is a pericardial cavity between the pericardium & heart which is occupied by pericardial fluid. This fluid protects the heart from shocks & keeps the heart moist.
- The walls of the heart are consist of three layers
1.Epicardium-outermost
2. Myocardium-middle layer & it is made up of Cardiac muscles.
3.Endocardium-Inner layer
- The anterior part of the heart is called an auricular part & the posterior part is called a ventricular part. There is a coronary sulcus between these 2 parts.
- The auricular pair is smaller & less muscular. It is divisible into 2 equal left & right auricles with the help of an interauricular septum.
- During the embryonic stage, the interauricular septum bears an oval pore, the foramen ovals. This pore get closed later & its scar is called as fossa ovals
