<prompt> Action potential is transmitted in myofibrils via:Terminal cisternsT- TubulesLongitudinalSarcomere  <response>: Ans: B T- Tubules Ref: Pal GK. Muscle, In: Textbook of Medical Physiology, Ahuja Publishing House 2007: 20:177Explanation:T-Tubules are tubular extensions of sarcolemma. that penetrate to the center at the junctions of A and I bands. It is involved in conduction of action potential from NMJ to the triad formed by terminal cisternae and L tubules part of sarcotubular system.Terminal cisternae - dilated region at both ends of elongated tubules L-tubules, a part of Sarcoplasmic reticulum - involved in calcium release. Sarcomere - structural functional unit of myofibril; portion of myofibril between two successive Z lines. 