Cardiac Muscle

The term cardiac muscle is used inter-changeably with the term "heart muscle". It is the specialized muscle that forms the walls of the heart.

The Structure of Cardiac Muscle:

Cardiac muscle has many similarities with skeletal muscle and also has some special features.

Studies using electron microscopes, which are more powerful than optical microscopes, show that cardiac muscle consists of a network of branching elongated cells whose junctions with other cells are marked by irregular transverse bands called intercalated discs that are located at the positions of the end-to-end attachments of the cells. Cardiac cells are joined to each other ionically by gap junctions.

• Cardiac muscle is striated but, unlike skeletal skeletal (striated), it is made up of a continuous, morphologically distinct network of branching and anastomosing cells.
• Cardiac muscle (in common with skeletal muscle), has actin and myosin microfilaments organized into sarcomeres.

Throughout life, cardiac muscle contracts about 70 times per minute pumping about 5 litres of blood each minute. See also the parts of the heart.

Other types of muscle tissue:

There are three main types of muscle tissue.
They are:

• Skeletal Muscle - muscles that move bones, under conscious control.
• Smooth Muscle - surrounding organs and other body structures, not under conscious control.
• Cardiac Muscle (see above) - the specialized muscle found only in the heart.