Which is not a component of the neuromuscular junction?

Which is not a component of the neuromuscular junction?

• A. Axon terminals
• B. Synaptic cleft
• C. ACh receptors on the sarcolemma
• D. Myofibrils

Answer: (D)

The neuromuscular junction is the synapse between a motor neuron and a muscle fiber, and it includes the presynaptic axon terminal that releases transmitter into the synaptic cleft and the postsynaptic ACh receptors on the sarcolemma that respond to acetylcholine to trigger a muscle impulse. The space between them is the synaptic cleft. Myofibrils, on the other hand, are the long contractile fibers inside the muscle cell that organize into sarcomeres to produce force. They reside within the muscle fiber itself, not at the junction where the nerve signal is transmitted. So, myofibrils are not a component of the neuromuscular junction.

The neuromuscular junction is the synapse between a motor neuron and a muscle fiber, and it includes the presynaptic axon terminal that releases transmitter into the synaptic cleft and the postsynaptic ACh receptors on the sarcolemma that respond to acetylcholine to trigger a muscle impulse. The space between them is the synaptic cleft. Myofibrils, on the other hand, are the long contractile fibers inside the muscle cell that organize into sarcomeres to produce force. They reside within the muscle fiber itself, not at the junction where the nerve signal is transmitted. So, myofibrils are not a component of the neuromuscular junction.