Answer :
Final answer:
Facial nerve palsy due to an upper motor neuron lesion usually shows with contralateral facial weakness while sparing the forehead area. UMN lesions also lead to symptoms like spasticity and heightened reflexes. Muscle strength tests help in distinguishing between UMN and LMN lesions.
Explanation:
Facial nerve palsy caused by an upper motor neuron (UMN) lesion typically presents with contralateral facial weakness but spares the forehead due to bilateral cortical representation. This means that the weakness is on the opposite side of the body from the lesion. However, lower segments of the face, which are only innervated by the contralateral hemisphere, display the weakness.
It's important to distinguish between UMN and lower motor neuron (LMN) lesions because they present differently. UMN lesions can lead to muscle weakness, increased deep tendon reflexes, and spasticity, among other symptoms. On the other hand, LMN lesions often cause flaccid paralysis, muscle atrophy, and decreased reflexes.
Testing muscle strength against resistance and observing for asymmetry can help in the diagnosis. For instance, if a patient can resist with the right arm but not the left, this may indicate a problem with one corticospinal tract over the other. Persistent weakness after repeated testing would reinforce the presence of a motor system deficit.
Learn more about Facial Nerve Palsy here:
https://brainly.com/question/28139458
#SPJ11
