👉 In physics and biomechanics, a myofibril is a type of muscle fiber. A myofibrilla is characterized by its small size and high tensile strength, which are important for maintaining muscle contraction in muscles like the diaphragm and abdominal muscles. Myofibrils are made up of two filaments, each composed of a protein called actin or sarcomere, and one myofilament. The actin filament is responsible for the contractility of the muscle fiber