The drooping corners of the mouth are mostly caused by scar contracture after burns that pull the corners of the mouth to shift, and can also be caused by the sequelae of trauma or noma. Unilateral facial nerve palsy in its advanced stage is accompanied by drooping corners of the mouth in addition to crooked corners of the mouth, all of which should be orthoplasty. The following diseases are also causes of orofacial ptosis: 1. Multiple peripheral neuritis Peripheral neuritis is a condition that in most cases is not an infection or inflammation, also known as peripheral neuropathy. The disease is caused by a variety of peripheral neuropathy (including cranial and spinal nerves), manifested as abnormalities in sensory, motor and vegetative nerve function within the damaged innervation, multiple or single, symmetric or asymmetric, and is a relatively common disease of the nervous system. It can develop at any age. Facial palsy is divided into two parts: the facial muscles, which are innervated by the facial nerve, and the masticatory muscles, which are innervated by the motor branch of the trigeminal nerve. Facial nerve palsy is more common in cerebral neurological disorders and is divided into five main types, including idiopathic (Bell), trauma, infection, tumor, and neurogenic, depending on the cause. Idiopathic facial nerve palsy, Bell’s palsy, is described in detail as a separate disease. Other types of facial nerve palsy are described here. 3, facial neuritis Idiopathic facial nerve palsy, namely facial neuritis, also known as Bell’s palsy, refers to an acute non-specific inflammation of the facial nerve in the facial nerve canal segment resulting in peripheral facial palsy. The cause of Bell’s palsy is not fully understood, but tends to be caused by a neurotropic virus; Ramsay Hunt syndrome is caused by herpes zoster virus.