motoneuron
Noun: A nerve cell (neuron) that transmits motor commands from the central nervous system (the brain or spinal cord) to muscles or glands, causing them to contract or secrete.
This is a specialized biological and medical term. It refers specifically to the final output neuron in a neural pathway that directly connects to and activates an effector organ (like a muscle fiber). * The signal from the brain traveled down the spinal cord and was relayed by a motoneuron to the leg muscle. * Damage to the motoneurons can result in conditions like amyotrophic lateral sclerosis (ALS). * The study focused on how motoneuron activity controls fine motor skills.
- Lower motoneuron: Refers to motoneurons whose cell bodies are located in the brainstem or spinal cord and whose axons directly innervate muscles. Damage here causes flaccid paralysis.
- Upper motoneuron: Refers to neurons in the cerebral cortex and brainstem that synapse onto and regulate the activity of lower motoneurons. Damage here typically causes spastic paralysis.
- The term is often used in clinical contexts to localize neurological lesions (e.g., "upper vs. lower motoneuron signs").
- Motor neuron: The more common and functionally identical synonym for "motoneuron."
- Efferent neuron: A broader term for any neuron that carries signals from the central nervous system, which includes motoneurons (somatic efferents) and neurons to glands (autonomic efferents).
- Motoneuronal (adj): Relating to motoneurons (e.g., motoneuronal disease).
- Motor neuron
- Efferent neuron (in a specific context)
- Final common pathway (a conceptual synonym emphasizing its role as the last neuron in a chain)
This term has a single, precise meaning in neuroscience and medicine. It does not have common idiomatic or figurative uses.
- a neuron conducting impulses outwards from the brain or spinal cord