Definition

1. Noun:
   • A neuron conducting impulses outwards from the brain or spinal cord: A motor nerve fiber is a type of nerve cell (neuron) that carries signals away from the central nervous system (the brain and spinal cord) to muscles or glands. This causes an effect, such as muscle contraction or gland secretion.

Usage

• The term "motor nerve fiber" is used in anatomical, physiological, and medical contexts to describe the specific part of the nervous system responsible for generating movement or action.
• It is typically used to distinguish these fibers from "sensory nerve fibers," which carry information the central nervous system.

Examples

• Noun:
  • Damage to a motor nerve fiber can result in paralysis of the muscle it supplies.
  • The signal travels along the motor nerve fiber from the spinal cord to the leg muscle, causing it to contract.

Advanced Usage

• "Lower motor neuron": This is a clinical synonym for the cell body and axon of a motor nerve fiber. Damage to these neurons causes specific clinical signs like muscle weakness, atrophy, and reduced reflexes.
• "Efferent fiber": This is a broader physiological term meaning "carrying away." All motor nerve fibers are efferent fibers, but not all efferent fibers are motor (some go to glands).

Variants and Related Words

• Motor neuron (n): Often used interchangeably with "motor nerve fiber," though technically the neuron includes the cell body, while the fiber is typically the axon.
• Efferent neuron (n): A synonym emphasizing the direction of signal conduction (away from the CNS).
• Motoneuron (n): A shortened, technical form of "motor neuron."

Synonyms

• Efferent nerve fiber: A synonym focusing on the conducting function.
• Motoneuron axon: A more precise term specifying the long, signal-transmitting part of the motor neuron.

Related Phrases

• Motor unit: A single motor nerve fiber and all the muscle fibers it innervates.
  • The strength of a muscle contraction depends on how many motor units are activated.
• Motor end plate: The specialized synapse where a motor nerve fiber connects with a muscle fiber.
  • The neurotransmitter released at the motor end plate triggers muscle contraction.

Noun

1. a neuron conducting impulses outwards from the brain or spinal cord