RT Book, Section A1 de Jesus, Matthew A2 Freeman, Brian S. A2 Berger, Jeffrey S. SR Print(0) ID 1102568844 T1 Skeletal Muscle Contraction T2 Anesthesiology Core Review: Part One Basic Exam YR 2014 FD 2014 PB McGraw-Hill Education PP New York, NY SN 9780071821377 LK accessanesthesiology.mhmedical.com/content.aspx?aid=1102568844 RD 2024/03/28 AB Voluntary skeletal muscle contraction occurs when an electrical signal (action potential) travels via somatic nerves to the synaptic cleft. Here, the electrical action potential opens voltage-gated calcium channels, and calcium causes the release of acetylcholine (ACh) into the synaptic cleft. The ACh travels across the synaptic cleft binding to nicotinic ACh receptors, which when activated, allow an influx of sodium ions into the muscle fiber membrane. The intracellular voltage change from the influx of sodium transmits an action potential via T-tubules to the center of the muscle cell, where upon reaching the sarcoplasmic reticulum, calcium ions are released, enabling muscle fibers to contract.