Each skeletal muscle fiber is controlled by a neuron at a single __________.

• A. varicosity
• B. neuromuscular junction
• C. synaptic knob
• D. transverse tubule
• E. sarcomere

Answer: (B)

Verified step by step guidance

1. Understand the context: Skeletal muscle fibers are controlled by neurons, which communicate with the muscle fibers to initiate contraction.
2. Identify the key term: The point where a neuron communicates with a muscle fiber is crucial for transmitting signals.
3. Define the term 'neuromuscular junction': This is the specific site where the motor neuron and muscle fiber meet, allowing for the transmission of nerve impulses to the muscle.
4. Differentiate between the options: A 'varicosity' is related to autonomic nervous system and smooth muscle, not skeletal muscle. A 'synaptic knob' is part of the neuron but not the specific site of communication with muscle fibers. A 'transverse tubule' is involved in conducting electrical signals within the muscle fiber, not the site of neuron-muscle communication. A 'sarcomere' is the functional unit of muscle contraction, not the site of neural control.
5. Conclude with the correct term: The 'neuromuscular junction' is the correct term for the site where a neuron controls a skeletal muscle fiber.