Facial nerve an incorrectly placed dental local-anesthetic (Inferior alveolar nerve block). Although giving the appearance of a hemi-plegic stroke, effects dissipate with the drug. When the facial nerve is permanently damaged due to a birth defect, trauma, or other disorder, surgery including a cross facial nerve graft or masseteric facial nerve transfer may be performed to help regain facial movement. Facial nerve decompression surgery is also sometimes carried out in certain cases of facial nerve compression. Voluntary facial movements, such as wrinkling the brow, showing teeth, frowning, closing the eyes tightly (inability to do so is called lagophthalmos) , pursing the lips
Facial nerve and puffing out the cheeks, all test the facial nerve. There should be no noticeable asymmetry. In an UMN lesion, called central seven, only the lower part of the face on the contralateral side will be affected, due to the bilateral control to the upper facial muscles (frontalis and orbicularis oculi). Lower motor neuron lesions can result in a CNVII palsy (Bell's palsy is the idiopathic form of facial nerve palsy), manifested as both upper and lower facial weakness on the same side of the lesion. Taste can be tested on the anterior 2/3 of the tongue. This can be