Terminal cisternae are discrete regions within the muscle cell store calcium. It is an enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules. It also serves as the reservoirs that store the calcium required for muscle contraction. The Calcium Release Unit Consists of Multiple Proteins on T-tubules and Sarcoplasmic Reticulum Membranes consists of the terminal cisternae of the sarcoplasmic reticulum and its adjacent transverse or T-tubule that is the invigilated part of the surface membrane. The dihydropyridine receptor (DHPR) and ryanodine receptor (RyR), the calcium release channel, on the sarcoplasmic reticulum are the two major proteins are the voltage sensor on the T-tubule.