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Palatal myoclonus is a rare condition in which there are rhythmic jerky movements or a rapid spasm of the palatal (roof of the mouth) muscles. Chronic clonus is often due to lesions of the central tegmental tract (which connects the red nucleus to the ipsilateral inferior olivary nucleus ).
Cross-section through the spiral organ of Corti at greater magnification, showing position of the hair cells on the basement membrane. The organ of Corti is located in the scala media of the cochlea of the inner ear between the vestibular duct and the tympanic duct and is composed of mechanosensory cells, known as hair cells. [2]
Middle ear myoclonus occurs in the muscles of the middle ear. These muscles may include the tensor tympani and stapedius muscles. It can involve the muscles surrounding the Eustachian tube, which include the tensor veli palatini, levator veli palatini, and salpingopharyngeus. Those affected describe it as a thumping sound or sensation in the ear.
Cortical deafness is a rare form of sensorineural hearing loss caused by damage to the primary auditory cortex. Cortical deafness is an auditory disorder where the patient is unable to hear sounds but has no apparent damage to the structures of the ear (see auditory system ).
The auditory cortex's function may help explain why particular brain damage leads to particular outcomes. For example, unilateral destruction, in a region of the auditory pathway above the cochlear nucleus, results in slight hearing loss, whereas bilateral destruction results in cortical deafness.
These subdivided cortical regions are later known as the Brodmann areas. Brodmann was the pioneer of cerebral cortex mapping. He grouped several cortical regions based on their nervous function, two of which are areas 41 and 42 for auditory processing. It has been suggested that Brodmann area 42 is a homotypical acoustic association area. [6]
Myoclonus is usually classified physiologically to optimize treatment. Myoclonus is a precursor effect to myoclonus dystonia and most commonly begins in childhood or adolescence. [4] [5] Myoclonus is classified as cortical, subcortical, peripheral or spinal. Cortical myoclonus is the most common of these four and affects the upper limbs and face.
The inner ear consists of the cochlea and several non-auditory structures. The cochlea has three fluid-filled sections (i.e. the scala media, scala tympani and scala vestibuli) , and supports a fluid wave driven by pressure across the basilar membrane separating two of the sections.