MICROANATOMY

Detailed explanation-1: -It is located at the junction of the crista terminalis in the upper wall of the right atrium and the opening of the superior vena cava. These cells have the ability to spontaneous generate an electrical impulse.

Detailed explanation-2: -The sinoatrial node (SAN), located in the right atrium, serves as the primary site for initiation of the normal heartbeat (sinus rhythm) (Figure 1).

Detailed explanation-3: -An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node). This is a small mass of specialized tissue located in the right upper chamber (atria) of the heart.

Detailed explanation-4: -The sinoatrial node is located in the upper part of the right atrium in the healthy heart, and serves as the natural pacemaker (Figure 1).

Detailed explanation-5: -A specialised cardiac musculature called the nodal tissue is also distributed in the heart. A patch of this tissue is present in the right upper corner of the right atrium called the sino-atrial node (SAN).