Question

Stimulation of a muscle fiber by a motor neuron occurs at

• A. the neuromuscular junction
• B. the transverse tubules
• C. the myofibril
• D. the sacroplasmic reticulum

Answer 1

The correct option is A the neuromuscular junction

During muscle contraction, a neural signal in the neuromuscular junction or motor-end plate releases a neurotransmitter, acetyl choline which generates an action potential in the sarcolemma.

Muscle contraction is initiated by a signal, sent by the central nervous system (CNS) via a motor neuron. Neuromuscular junction refers to the junction between a motor neuron and the sarcolemma of the muscle fiber.

A neural signal reaching this junction releases a neurotransmitter (Acetylcholine) which stimulates the muscle fibre by generating an action potential in the sarcolemma.

Hence stimulation of muscle fiber by a motor neuron occurs at the neuromuscular junction. So, the correct answer is 'Neuromuscular junction'.