Human muscles are classified into three types depending on location, function and structure. These three types are: $1)$ Skeletal or striated or voluntary $2)$ Smooth or involuntary or non striated $3)$ Cardiac muscles

Cardiac muscles are muscles related to the walls of the heart. These muscles are structurally like skeletal but functionally resemble smooth muscles. These have striations and thus contraction and relaxation results use muscle proteins like troponin , actin , myosin and tropomyosin. Gap junctions are seen in smooth and cardiac muscle.