Function and Lesions of Nucleus Ambiguus
- Controls motor innervation of ipsilateral muscles of the soft palate, pharynx, larynx, and upper esophagus
- Lesions result in nasal speech, dysphagia, dysphonia, and deviation of the uvula toward the contralateral side
- Plays a role in speech and swallowing
- Innervates postganglionic parasympathetic neurons in the heart
Areas supplied by Nucleus Ambiguus
- Muscles supplied by the vagus nerve, including levator veli palatini, are necessary for proper swallowing
- Integration by the nucleus of the solitary tract is involved in swallowing
- Vagus nerve supplies upper part of the esophagus, pharynx, and larynx
- External formation of the nucleus ambiguus contains cholinergic preganglionic parasympathetic neurons for the heart
- These neurons have a cardioinhibitory effect
Cardiac and Bronchopulmonary Effects of Nucleus Ambiguus
- Nucleus ambiguus, along with sympathetic outflow, regulates quick changes in blood pressure
- Parasympathetic outflow from the nucleus ambiguus and dorsal motor nucleus of the vagus nerve decreases cardiac activity in response to fast increases in blood pressure
- External formation of the nucleus ambiguus sends bronchoconstrictor fibers to the bronchopulmonary system
- This can cause reflexive decreases in pulmonary bronchial airflow
- Role in bronchospastic diseases like COPD/emphysema and asthma, particularly for exercise-related asthma exacerbations
Additional Images of Nucleus Ambiguus
- Section of the medulla oblongata at about the middle of the olive
- Schematic representation of cranial nerve nuclei, showing motor nuclei in red and sensory nuclei in blue
- Schematic representation of nuclei of origin of cranial motor nerves, shown in a lateral view
- Transverse section of the medulla oblongata, showing the formatio reticularis
- Images provide visual representation of the nucleus ambiguus and its location in the medulla oblongata
Related Concepts and References
- Solitary nucleus, another important nucleus in the medulla oblongata
- Related nucleus involved in sensory processing and integration
- Provides additional context and understanding of the neural circuitry in the medulla oblongata
- Relevant research articles and studies related to the nucleus ambiguus and its functions
- Additional resources and information for further exploration of the topic provided by Medical Neurosciences
The nucleus ambiguus ("ambiguous nucleus" in English) is a group of large motor neurons, situated deep in the medullary reticular formation named by Jacob Clarke. The nucleus ambiguus contains the cell bodies of neurons that innervate the muscles of the soft palate, pharynx, and larynx which are associated with speech and swallowing. As well as motor neurons, the nucleus ambiguus contains preganglionic parasympathetic neurons which innervate postganglionic parasympathetic neurons in the heart.
| Nucleus ambiguus | |
|---|---|
 Transverse section of medulla oblongata below the middle of the olive. ("Nucleus ambiguus" labeled at center right.) | |
| Details | |
| Identifiers | |
| Latin | nucleus ambiguus |
| NeuroNames | 765 |
| NeuroLex ID | birnlex_2650 |
| TA98 | A14.1.04.253 |
| TA2 | 6011 |
| FMA | 54588 |
| Anatomical terms of neuroanatomy | |
It is a region of histologically disparate cells located just dorsal (posterior) to the inferior olivary nucleus in the lateral portion of the upper (rostral) medulla. It receives upper motor neuron innervation directly via the corticobulbar tract.
This nucleus gives rise to the branchial efferent motor fibers of the vagus nerve (CN X) terminating in the laryngeal, pharyngeal muscles, and musculus uvulae[citation needed]; as well as to the efferent motor fibers of the glossopharyngeal nerve (CN IX) terminating in the stylopharyngeus muscle.
nucleus ambiguus
