Final answer:
True, more sodium is found outside the muscle fiber at rest due to the activity of the sodium-potassium pump, which is essential for maintaining the muscle cell's resting membrane potential and for initiating contractions.
Step-by-step explanation:
True, when a skeletal muscle fiber is at rest, there is indeed more sodium outside of the cell than inside the sarcoplasm. Muscle fibers are composed of myofibrils which exhibit a banding pattern due to the organization of actin and myosin. The resting membrane potential is maintained by the sodium-potassium pump which actively transports three sodium ions out of the cell for every two potassium ions it brings in, establishing a higher concentration of sodium outside of the muscle cell.
This ionic distribution is critical for the action potential that initiates muscle contraction. Overall, the higher sodium concentration outside the cell is essential for the initiation of muscle contraction when an action potential is generated.