The muscle cell cytoplasm containing myofibrils is called?

• A. Cytoplasm
• B. Mitochondrion
• C. Sarcoplasm
• D. Nucleoplasm

Answer: (C)

The term for the cytoplasm of a muscle fiber that contains the contractile elements is sarcoplasm. In muscle tissue, the interior of the cell is named sarcoplasm to reflect its specialized content—the myofibrils organized into sarcomeres that drive contraction, along with mitochondria and the sarcoplasmic reticulum that helps regulate calcium during this process. While cytoplasm is the general term for the cell’s interior, sarcoplasm highlights the muscle-specific environment where the contractile machinery operates. Nucleoplasm is the fluid inside the nucleus, and mitochondrion is an energy-producing organelle found within the cytoplasm (sarcoplasm) of the muscle cell.