Point 9












Deviation of the UvulaA unilateral lesion of nucleus ambiguus will result in atrophy and paralysis of all palatine muscles ipsilateral to the lesion, except the tensor veli palatini (C.N. V). Because of the palate paralysis, the patient's speech may be nasal. This is because air is allowed to escape into the nose during speaking. Normally, the soft palate elevates in order to reduce the nasopharyngeal aperture during speaking. This elevation of the soft palate detours the air through the mouth, the path of least resistance. Due to the hemiplegic palate the patient may complain of nasal regurgitation of liquids since he/she is unable to shut off completely the nasopharynx from the buccal cavity. Moreover, during phonation (say ahhh!) the soft palate is elevated on the normal side and the UVULA DEVIATES TOWARDS THE NORMAL SIDE (contralateral to the lesion; contrast this with lesions of the hypoglossal nucleus). Remember from Gross Anatomy that the levator veli palatini raises the soft palate and, in doing so, also pulls it backward. Also, some awkwardness of swallowing, called dysphagia, may occur due to the unilateral paralysis of the constrictors of the pharynx. Due to paralysis of the laryngeal muscles, the patient exhibits dysphonia, his/her voice being husky or hoarse (speech requires phonation by the vocal cords; phono=voice, sound).

Muscles of the PalateBilateral lesions of nucleus ambiguus increase the difficulties I have just described following ipsilateral lesions. Nasal regurgitation is more distressing and permanent. Dysphagia is more pronounced and speech and respiratory disorders may be profound. Respiratory disorders, induced by the paralysis of the abductor muscles (of the larynx) bilaterally may lead to suffocation unless treated by intubation.