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Polyvagal theory views the parasympathetic nervous system as being split into two distinct branches: a "ventral vagal system" which supports social engagement, and a "dorsal vagal system" which supports immobilisation behaviours, both "rest and digest" and defensive immobilisation or "shutdown". [14]
The dorsal nucleus of vagus nerve (or posterior nucleus of vagus nerve or dorsal vagal nucleus or nucleus dorsalis nervi vagi or nucleus posterior nervi vagi) [1] is a cranial nerve nucleus of the vagus nerve (CN X) situated in the medulla oblongata of the brainstem ventral to the floor of the fourth ventricle.
The SE therapy concepts such as "dorsal vagal shutdown" with bradycardia that are used to describe "freeze" and collapse states of trauma patients are controversial since it appears the ventral vagal branch, not the dorsal vagal branch, mediates this lowered heart rate and blood pressure state.
It is excited by visceral afferent impulses (sympathetic and vagal) arising from the gastrointestinal tract and other peripheral trigger zones, and by humoral factors. [2] The area postrema makes up part of the dorsal vagal complex, which is the critical termination site of vagal afferent nerve fibers , along with the dorsal motor nucleus of ...
Vagovagal reflex refers to gastrointestinal tract reflex circuits where afferent and efferent fibers of the vagus nerve [1] coordinate responses to gut stimuli via the dorsal vagal complex in the brain. The vagovagal reflex controls contraction of the gastrointestinal muscle layers in response to distension of the tract by food.
The vagus nerve is also responsible for regulating inflammation in the body, via the inflammatory reflex. [7] Efferent vagus nerve fibers innervating the pharynx and back of the throat are responsible for the gag reflex. In addition, 5-HT 3 receptor-mediated afferent vagus stimulation in the gut due to gastroenteritis is a cause of vomiting. [8]
Micrograph of the posterior portion of the open part of the medulla oblongata, showing the fourth ventricle (top of image) and the hypoglossal nucleus (medial - left of image) and the dorsal motor nucleus of the vagus nerve (lateral - right of image). H&E-LFB stain. Hypoglossal nucleus (XII) - motor; Dorsal motor nucleus of vagus nerve (X ...
Vagal tone is activity of the vagus nerve (the 10th cranial nerve) and a fundamental component of the parasympathetic branch of the autonomic nervous system. This branch of the nervous system is not under conscious control and is largely responsible for the regulation of several body compartments at rest.