Cardiac muscle

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Cardiac muscle tissue (myocardium) consists of individual, branched, mostly mononuclear heart muscle cells, called cardiomyocytes. These  are connected to each other via adhesive contacts and gap junctions (shiny stripes) and thus form a functional syncytium. Similar to skeletal muscle, cardiac muscle shows striations under the microscope, but its overall structure is more reticulated and branched. In addition, connective tissue, blood vessels and nerve fibers are also found in the myocardium.

The myocardium is innervated both by the autonomic nervous system as well as by specialized heart muscle cells that can activate themselves and cause the tissue to contract. These pacemaker cells are located in the sinus node, AV node and in the conduction bundle of the heart chambers and together they form the cardiac conduction system.

Watch the following video to learn more about the structure of cardiac muscle and its histological appearance:

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