From the Guidelines
The nucleus ambiguus is located in the medulla oblongata, as indicated by the most recent study on cranial neuropathy from 2022 1. This location is critical for the function of the nucleus ambiguus, which contains lower motor neurons contributing to the formation of cranial nerves IX, X, and XI.
- The medulla oblongata is a key structure in the brainstem, and the nucleus ambiguus is positioned within it, specifically in the lateral portion of the reticular formation.
- The study from 2022 1 mentions the nucleus ambiguus in the context of the accessory nerve (CN XI), highlighting its origin within the medulla oblongata.
- The nucleus ambiguus plays essential roles in controlling muscles involved in swallowing, phonation, and certain aspects of cardiovascular regulation, making its location in the medulla oblongata crucial for these functions.
- The integration of the nucleus ambiguus with nearby autonomic centers in the medulla allows it to participate in vital reflexes, further emphasizing the importance of its location in the medulla oblongata, as supported by the recent study 1.
From the Research
Nucleus Ambigus Location
The nucleus ambigus is a group of neurons located in the medulla oblongata, which is the lowest part of the brainstem.
- It is positioned rostrally to the crossing pyramidal fibers and laterally to the crossing lemnisces, as described in a study published in 1986 2.
- The lateral reticular nucleus is situated laterally and ventrally to the neurons of the connection between the nucleus retroambiguus and the nucleus ambiguus.
- The neurons belonging to this connection are medium-sized, with long dendrites directed mainly medially, dorsally, and ventrally, and medially directed dendrites that ascend into the central nucleus of the medulla oblongata.
Relation to Other Brain Structures
- Fibers of the lateral vestibulobulbospinal tract pass through the area of the connection between the nucleus retroambiguus and the nucleus ambiguus 2.
- The tracts of the corticobulbar and medial reticular formations are found in the vicinity of the neuronal group described above.
- The nucleus ambigus is also involved in the complex network of neurons that coordinate normal swallowing, as revealed by animal and human studies 3.
Clinical Significance
- Damage to the brainstem, including the nucleus ambigus, can result in dysphagia, as seen in patients with brainstem stroke 4, 5, 6.
- The incidence of dysphagia is relatively high in patients with brainstem stroke, and the long-term outcome can be favorable with appropriate treatment and rehabilitation 4, 5.