sarcoplasmic reticulum /-plas″mik/ [Gk, sarx + plassein, to mold; L, reticulum, little net] , a network of tubules and sacs in skeletal muscle fibers that plays an important role in muscle contraction and relaxation by releasing and storing calcium ions. This network is analogous, but not identical, to the endoplasmic reticulum of other cells.
