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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. Because of these lesions, the facial motor nucleus reduces or destroys input in the ventral division. [1]
By contrast, a lower motor neuron lesion to the facial motor nucleus results in paralysis of facial muscles on the same side of the injury. If a cause, such as trauma or infection, cannot be identified (this situation is called idiopathic palsy) this condition is known as Bell's palsy. Otherwise it is described by its cause.
Glutamate released from the upper motor neurons triggers depolarization in the lower motor neurons in the anterior grey column, which in turn causes an action potential to propagate the length of the axon to the neuromuscular junction where acetylcholine is released to carry the signal across the synaptic cleft to the postsynaptic receptors of the muscle cell membrane, signaling the muscle to ...
Facial weakness is a medical sign associated with a variety of medical conditions. [1] Some specific conditions associated with facial weakness include: [citation needed] Stroke; Neurofibromatosis; Bell's palsy; Ramsay Hunt syndrome; Spontaneous cerebrospinal fluid leak; Myasthenia gravis
Changes in muscle performance can be broadly described as the upper motor neuron syndrome. These changes vary depending on the site and the extent of the lesion, and may include: Muscle weakness. [2] known as 'pyramidal weakness' Decreased control of active movement, particularly slowness; Spasticity, a velocity-dependent change in muscle tone
The upper motor neuron descends in the spinal cord to the level of the appropriate spinal nerve root. At this point, the upper motor neuron synapses with the lower motor neuron or interneurons within the ventral horn of the spinal cord , each of whose axons innervate a fiber of skeletal muscle.
The facial paralysis can follow immediately the trauma due to direct damage to the facial nerve, in such cases a surgical treatment may be attempted. In other cases the facial paralysis can occur a long time after the trauma due to oedema and inflammation. In those cases steroids can be a good help.
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)