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Conversely, a lower motor neuron lesion affects nerve fibers traveling from the anterior horn of the spinal cord or the cranial motor nuclei to the relevant muscle(s). [ 1 ] Upper motor neuron lesions occur in the brain or the spinal cord as the result of stroke , multiple sclerosis , traumatic brain injury , cerebral palsy , atypical ...
Upper motor neuron syndrome (UMNS) is the motor control changes that can occur in skeletal muscle after an upper motor neuron lesion. Following upper motor neuron lesions, affected muscles potentially have many features of altered performance including: weakness (decreased ability for the muscle to generate force)
Hypertonia is a term sometimes used synonymously with spasticity and rigidity in the literature surrounding damage to the central nervous system, namely upper motor neuron lesions. [1] Impaired ability of damaged motor neurons to regulate descending pathways gives rise to disordered spinal reflexes , increased excitability of muscle spindles ...
Upper motor neurons (UMNs) is a term introduced by William Gowers in 1886. They are found in the cerebral cortex and brainstem and carry information down to activate interneurons and lower motor neurons, which in turn directly signal muscles to contract or relax. UMNs represent the major origin point for voluntary somatic movement.
Upper motor neurons originating in the primary motor cortex synapse to either lower motor neurons in the anterior horn of the central gray matter of the spinal cord (insert) or brainstem motor neurons (not shown). Motor neuron disease can affect either upper motor neurons (UMNs) or lower motor neurons (LMNs). Motor neuron disease describes a ...
[2] [4] Through this pathway the basal ganglia is able to initiate voluntary movements by disinhibiting thalamic neurons that drive upper motor neurons. [1] This process is regulated by dopamine secreted by the striatum onto the D 1 dopamine receptor on the SNc. Dopamine excites striatal neurons in the direct pathway. [5]
The defining feature of ALS is the death of both upper motor neurons (located in the motor cortex of the brain) and lower motor neurons (located in the brainstem and spinal cord). [77] In ALS with frontotemporal dementia, neurons throughout the frontal and temporal lobes of the brain die as well. [78]
This condition is often the result of damage of the upper motor neurons of the facial nerve. The facial motor nucleus contains ventral and dorsal areas that have lower motor neurons that supply the upper and lower face muscles. When central facial palsy occurs, there are lesions in the corticobulbar tract between the cerebral cortex.