ABSTRACT
The internal structure of a muscle fibre is shown in Figure 24.5. The surface of each muscle fibre is covered by a cell membrane, the sarcolemma. Packed in the cytoplasm of the fibre, running from one end to the other, there are bundles of myofibrils composed of interdigitating thin filaments (actin+tropomyosin+ troponin) and thick filaments (myosin), together with two tubular conducting systems and mitochondria.
