04 - Skeletal Muscles

neuromuscular junction

synaptic connection between a motor nerve and a skeletal muscle

motor nerves

Nerves that regulate skeletal muscle

How Nerves Control Muscles

🔹 Action Potential Arrival

• An electrical signal (action potential) travels down the motor neuron to the axon terminal.

🔹 Neurotransmitter Release

• The action potential triggers the release of acetylcholine (Ach) from membrane-bound vesicles into the synaptic cleft (between the pre-synaptic cell (the neuron), and the post-synaptic cell (the muscle fibre)).

🔹 Receptor Binding & Ion Channel Activation

• Ach binds to nicotinic acetylcholine receptors on the post-synaptic membrane (sarcolemma).

• These receptors act as Na+ (sodium) channels.

🔹 Muscle Cell Depolarization

• Na+ ions enter the muscle cell → Depolarization occurs → Triggers a muscle action potential → Leads to muscle contraction.

muscle fibres

Skeletal muscle cells are called muscle fibres.

Skeletal muscle cells