A motor neuron along with all the muscle fibers it supplies is called a(n) __________.

• A. synaptic cleft
• B. axon terminal
• C. motor unit
• D. motor end plate
• E. neuromuscular junction

Answer: (C)

Verified step by step guidance

1. Begin by understanding the components involved in muscle contraction. A motor neuron is a nerve cell that transmits signals from the brain or spinal cord to muscles, causing them to contract.
2. Recognize that a motor neuron connects to multiple muscle fibers, forming a functional unit responsible for muscle contraction.
3. Identify the term that describes this combination of a motor neuron and the muscle fibers it innervates. This is known as a 'motor unit'.
4. Differentiate between related terms: 'synaptic cleft' is the gap between neurons, 'axon terminal' is the end of a neuron, 'motor end plate' is the region of the muscle fiber membrane, and 'neuromuscular junction' is the site where a motor neuron communicates with a muscle fiber.
5. Conclude that the correct term for a motor neuron and all the muscle fibers it supplies is 'motor unit', which is essential for understanding how muscles are controlled and coordinated.