How does an action potential rapidly spread to the central portions of a muscle cell?

Question

Quizplus · Accepted Answer

Action potential rapidly spreads to the central portions of a muscle cell by means of T tubules, which are invaginations of the cell membrane that penetrate into the muscle fiber and allow for the transmission of the action potential deep into the interior of the cell. This helps to trigger the release of calcium ions from the sarcoplasmic reticulum, leading to muscle contraction.

How Does an Action Potential Rapidly Spread to the Central