Síndromes motores
- Roa Escobar, J. 1
- García Leal, A. 1
- Corral Quereda, C. 1
- Estebas Armas, C. 1
- Mariño Trillo, E. 1
- García Yu, R. 1
- González Sarmiento, R. 1
- Hernández Barral, M. 1
- 1 Servicio de Neurología y Centro de Ictus. IdiPAZ. Hospital Universitario La Paz-Universidad Autónoma de Madrid. Madrid. España
ISSN: 0304-5412
Year of publication: 2023
Issue Title: Enfermedades del sistema nervioso (VI): Síndromes motores, sensitivos y del sistema nervioso central y periférico
Series: 13
Issue: 75
Pages: 4415-4427
Type: Article
More publications in: Medicine: Programa de Formación Médica Continuada Acreditado
Abstract
The motor system has its origins in motor neurons (upper motor neuron) of the precentral gyrus of the frontal lobe (primary motor cortex, Brodmann area 4), and in the adjacent cortical areas. The axons of these cells constitute the pyramidal tract that descends through the corona radiata, internal capsule, and cerebral peduncles. In the brainstem, part of these motor fibers synapse with the brainstem motor nuclei. The rest continue descending through the brainstem, decussate in the medullary pyramid area, and descend through the spinal cord until the anterior horn, where they synapse with the inferior motor neuron. The axons of the inferior motor neurons pass through the anterior roots, nerve plexi, and peripheral nerves until they reach the skeletal muscle. The impulses are transmitted to muscle cells through the end plates of the neuromuscular junction. Lesions in the superior motor neuron cause spastic paresis and hyperreflexia. Lesions in the inferior motor neuron cause flaccid paralysis and hyporeflexia. Lesions in the peripheral nerve cause flaccid paralysis frequently associated with sensory abnormalities. Fatiguability is characteristic of disorders neuromuscular junction disorders and myopathies generate muscle weakness, atrophy, and myalgia.