What is the Nucleus Ambiguus?

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  • Written By: Meshell Powell
  • Edited By: Jacob Harkins
  • Last Modified Date: 18 January 2020
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The nucleus ambiguus is a nucleus with an elongated shape that is located in the medulla oblongata. This nucleus is basically a continuation of cells contained in the ventral horn area of the spinal cord. The cells that are present in this nucleus have an association with some of the cranial nerves, particularly the vagus and glossopharyngeal nerves.

The nucleus ambiguus basically consists of a thin column of motor neurons in the medulla oblongata. The medulla oblongata is the lower part of the brain stem. This type of nucleus supplies nerves to the muscles of the larynx as well as the pharynx. It also works to supply nerves to the soft palate.

Since the nucleus ambiguus is located in the brain stem, there is significant risk of damage, particularly due to the presence and appearance of lesions. There are a number of health issues that can arise as a result of these lesions. Medical assistance is required for proper diagnosis and treatment of any injury arising from this area of the body.

A lesion that presents on one side of this type of nucleus has the potential to cause muscle paralysis and atrophy in the areas surrounding the lesion. When the palate becomes paralyzed, speech is almost certain to be affected. This is a result of air escaping into the nose when the patient speaks. In this situation, it is also possible for liquids to be regurgitated through the nose.


If the constrictors located in the pharynx become paralyzed due to lesions, a condition referred to as dysphagia may occur. Dysphagia is the medical term for having difficulty when swallowing. This can range from mildly annoying to being severely debilitating. Sometimes the lesions cause paralysis of the laryngeal muscles. When this happens, the resulting condition is known as dysphonia. This causes the voice to sound hoarse or become husky.

Lesions affecting both sides of the nucleus affect the same areas of the body as do the lesions affecting only one side. Unfortunately, in this case, the effects of the paralysis can be much more severe. In many cases, the damage done also becomes permanent.

When lesions involve both sides of the nucleus ambiguus, many functions that we take for granted are severely compromised. For instance, the ability to swallow voluntarily can completely disappear. Respiratory problems can be severe, and normal speech could be lost forever. Breathing can become compromised to the point of suffocation without immediate and aggressive medical treatment.


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