Definition

1. Noun:
   • A nerve that conveys impulses toward or to muscles or glands: A motor nerve is a type of nerve fiber that carries signals from the central nervous system (the brain and spinal cord) to muscles or glands, causing them to contract or secrete. This is in contrast to sensory nerves, which carry information from the body to the central nervous system.

Usage Examples

• Noun:
  • Damage to a motor nerve can result in muscle weakness or paralysis.
  • The facial motor nerve controls the muscles used for smiling and frowning.
  • The doctor tested the patient's reflexes to assess the function of the motor nerves.

Advanced Usage

• "Lower motor nerve": Refers to motor nerves whose cell bodies are located in the spinal cord or brainstem and whose axons connect directly to muscles. Damage here causes flaccid paralysis.

  • The symptoms indicated a lesion in the lower motor nerve.

• "Upper motor nerve": Typically refers to neurons in the brain that send signals down to lower motor nerves. Damage here often causes spastic paralysis.

  • The stroke affected his upper motor neurons, leading to increased muscle tone.

Variants and Related Words

• Motor neuron (n): Often used interchangeably with "motor nerve," though technically a motor neuron is the nerve cell, while a motor nerve is the bundle of axons. It is the fundamental unit of the motor pathway.

  • Amyotrophic lateral sclerosis (ALS) is a disease that affects motor neurons.

• Efferent nerve (n): A more technical synonym for motor nerve, emphasizing that it carries signals away from the central nervous system.

  • The efferent nerves are crucial for voluntary movement.

Synonyms

• Efferent nerve: A nerve that conducts impulses outwards from the central nervous system.
• Motor neuron: A neuron that conveys impulses to a muscle, gland, or other effector organ.

Related Phrases

• Motor nerve conduction study: A diagnostic test that measures the speed and strength of electrical impulses traveling through a motor nerve.

  • The neurologist ordered a motor nerve conduction study to pinpoint the problem.

• Mixed nerve: A nerve containing both sensory and motor nerve fibers. Most peripheral nerves are mixed.

  • The sciatic nerve is a large mixed nerve.

Noun

1. a nerve that conveys impulses toward or to muscles or glands