The membranous network that wraps around myofibrils and holds relatively high concentrations of calcium is known as the

It is known as the sarcoplasmic reticulum. It is a particular sort of smooth ER that controls the calcium particle fixation in the cytoplasm of striated muscle cells.

The unique kind of smooth endoplasmic reticulum found in smooth and striated muscle filaments whose capacity is to store and discharge calcium particles. The sarcoplasmic reticulum discharges calcium particles amid muscle constriction and retains them amid unwinding.