-Aqsa, Subject Matter Expert at Edumarz.
Solution: The three features of cardiac muscles are:
The cardiac muscles are short, cylindrical cells with a single nucleus. They are striated both longitudinally and transversely. These muscle fibers are branched and interdigitate. The two adjacent fibers unite with each other through the extensive series of their membrane folds. The junctions, which always occur at the z line, are called intercalated discs.
The cardiac muscles are not structural syncytium, even though there are no protoplasmic bridges between the cells. Cardiac muscle fibers are also composed of myofibrils having a large number of mitochondria in contact.
The cardiac muscles remain supplied by both sympathetic and parasympathetic nerves. They contract quickly and do not undergo fatigue. They are self excitatory muscles.