Cardiac Muscle is the muscle that is found in the wall of heart.  It is striated like skeletal muscle, meaning that it contains the same arrangement of contractile filaments as skeletal muscle.  Cardiac fibers are long cylindrical cells with one or at times two nuclei which are centrally located.   A defining characteristic of cardiac muscle when viewing microscopically, besides the striations, is  its "y" shaped fiber orientation.   Between the fibers ends  are specialized intracellular junctions called intercalated discs.  The fibers, as like smooth muscle, are arranged in a syncitium and are not individually innervated. To find out more about purkinje fibers click here.

Here is a longitudinal section (A) and a transverse section (B) of cardiac muscle.  Again notice the "y" shaped orientation and the striations.  In the transverse section note the centrally located nuclei (N). To see a tranverse section of cardiac muscle click here.

Slide A

SlideB