Sarcolemma, sarcoplasm and sarcoplasmic reticulum refer to a particular type of cell in our body. Which is this cell and to what parts of that cell do these names refer to?

These names refer to the muscle cells or muscle fibres. They are lined by a plasma membrane, which is known as sarcolemma, which encloses the sarcoplasm. The sarcoplasmic reticulum refers to the endoplasmic reticulum of the muscle cells, which acts as a storehouse for calcium ions.