There are three main types of muscles: skeletal, cardiac, and smooth.
Skeletal muscle fibers are located in muscles attached to the skeleton. These muscles provide the movements of the body parts and support the posture of the body. They consist of striated fibers composed of myosin and actin fibers arranged in a repetitive unit (a sarcomere) separated the sarcolemma.
Cardiac muscles occur in the walls of the heart and provide the heart contraction. Cardiac muscles are similar to skeletal muscles as these fibers are striated. However, separate muscle fibers are connected via specific junctions. As a result, cardiac muscle contracts as a single unit.
Smooth muscles are located in the walls of visceral organs. These fibers are spindle-shaped and contract to move the content of the hollow organ or regulate its diameter and volume (i.e., vessels or digestive tract).