Organ
Nucleus ambiguus
Medullary output for swallowing, voice and cardiac control
High-yield
For its branchial motor output, remember IX to stylopharyngeus and X to most of the remaining swallowing and voice muscles. Tensor veli palatini is supplied by V3, not this nucleus.
Overview
This medullary motor column supplies stylopharyngeus through CN IX and many palatal, pharyngeal and laryngeal muscles through CN X. It also contains vagal preganglionic neurons involved in cardiac regulation. Traditional accounts describe a cranial accessory contribution, although its classification separately from the vagus remains disputed.
Reference facts
- Location
- Deep in the ventrolateral medullary reticular formation, behind the inferior olivary region.
- Parts
- A longitudinal population with branchial motor neurons and cardiac vagal preganglionic neurons. Its outputs are carried mainly in IX and X.
- Relations
- Located in lateral medullary tissue supplied by branches of the vertebral and posterior inferior cerebellar arterial systems.
- Function
- Activates stylopharyngeus, most soft-palate and pharyngeal muscles, laryngeal muscles and upper esophageal striated muscle; its cardiac vagal neurons help regulate heart rate.
Clinical correlation
Lateral medullary injury involving this nucleus and associated pathways may cause dysphagia and hoarseness. Unilateral vagal weakness can lower the affected side of the palate, with the uvula tending toward the stronger side; these findings depend on the extent of injury.
Frequently asked questions
Where is the nucleus ambiguus located?
Deep in the ventrolateral medullary reticular formation, behind the inferior olivary region.
What does the nucleus ambiguus do?
Activates stylopharyngeus, most soft-palate and pharyngeal muscles, laryngeal muscles and upper esophageal striated muscle; its cardiac vagal neurons help regulate heart rate.
What are the parts of the nucleus ambiguus?
A longitudinal population with branchial motor neurons and cardiac vagal preganglionic neurons. Its outputs are carried mainly in IX and X.