THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The heart muscle is the myocardium or middle layer of the heart walls. The myocardium is responsible for the contractile function of the cardiac pump.

Detailed explanation-2: -The myocardium is the muscular layer of the heart. It consists of cardiac muscle cells (cardiac myocytes [also known as cardiac rhabdomyocytes] or cardiomyocytes) arranged in overlapping spiral patterns.

Detailed explanation-3: -Cardiac muscle, also called the myocardium, is one of three major categories of muscles found within the human body, along with smooth muscle and skeletal muscle. Cardiac muscle, like skeletal muscle, is made up of sarcomeres that allow for contractility.