 Dear students, in this topic, we shall discuss the role of TT-views in the propagation of action potential into the myofibril. The action potential which arrives at the neuromuscular junction causes a potential difference across the surface of the muscle cell membrane. This action potential directly affects only less than a micrometer area of the membrane. However, you know that skeletal muscle fibers are about 50 to 100 micrometers in diameter. So a small action potential that spreads along the surface membrane cannot cause the grunt to flow deep into the thick muscle fiber. To spread this grunt deep into the muscle fiber, the muscle fibers have a specialized mechanism. This mechanism involves transmission of action potentials along specialized transverse tubules. These TT-views couple the depolarization at the surface of the membrane to deeper parts that is the myofibrils. The TT-views are very thin internal extensions of cell membrane which are less than 0.1 micrometer in diameter. These TT-views innovate on the Z-disc level in the cell and make the around branching network of each myofibril. This TT-view system provides an atomic link between the surface membrane and the myofibrils deep inside the muscle fiber. When an action potential spreads on the muscle fiber membrane, then it also spreads along the TT-views which are in the deeper parts of the muscle. This there is a deeper parts of the muscle tuck action potential because of presence of these TT-views. Dear students, inside the cell these TT-views are also linked to the sarcoplasmic reticulum. The sarcoplasmic reticulum releases calcium ions on the stimulation of action potential transmitted through the TT-views. These release of calcium ions permit the myocine cross bridges to attach and generate force for contraction.