Both skeletal muscles and cardiac muscles contain striations among muscle cells and produce strong contractions, according to class notes from Yale University. Striations occur in crossing, alternating light and dark bands produced by proteins that make muscles contract, according to Dictionary.com.
Cardiac muscles produce powerful contractions, but the mechanism behind the squeezing of cardiac muscle fibers differs from skeletal muscles. Cardiac fibers move due to changes in hormone levels and because of messages from the autonomic nervous system. This system regulates the heart muscles automatically without a person thinking about it. Contrarily, skeletal muscles contract when someone thinks to move a hand, arm, leg or other bone, explains Yale University.
Striations occur in both skeletal and cardiac muscles when fibers and proteins cross over each other, similar to a chess board. Cardiac striations branch out at the end of muscle fibers to create a complex web of three-dimensional tissue with adjacent cells, according to Yale University. Skeletal muscle cells and cardiac muscle cells also contain large amounts of mitochondria, the organelle that stores and creates energy from glucose within each cell.
Muscle cells in both cardiac and skeletal muscles are parallel to each other, but cardiac muscles are less parallel due to the branching off points at the end of fibers, states the University of Michigan Medical School. These muscle fibers appear longitudinally in a microscope, meaning they form horizontal stripes from left to right in the image.