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Vagus nerve

Vagus nerve nuclei & their central connections

Nuclei of the vagus nerve

1) Main motor nucleus 1. Receives corticonuclear fibers from both cerebral hemispheres
2. Supplies the constrictor muscles of the pharynx & the intrinsic muscles of the larynx
2) Parasympathetic nucleus (Dorsal nucleus) 1. Afferents from Hypothalamus & Glossopharyngeal nerve (Carotid sinus reflex)
2. Efferents to involuntary muscles of Bronchi, Heart, Esophagus, Stomach, Small intestine & Large intestine (up to distal 1/3 of the transverse colon)
3) Sensory nucleus (Lower part of the nucleus of the tractus solitarius) Efferents ends in post central gyrus of the cerebral cortex after going through the opposite thalamus
Examination of the vagus & glossopharyngeal nerves
1) Note patient’s voice : Voice is high pitched if the vocal cords are paralyzed (X nerve palsy)
2) Note any swallowing difficulty or regurgitation of fluid
3) Ask the patient to open his mouth & say ‘Ah’ – Note any asymmetry of the palatal movements (X nerve palsy)
4) Gag reflex : Depress the tongue & touch the palate, pharynx or tonsil (One side) until the patient gags (Compare the sensitivity of both sides)
a. Afferent : IX nerve
b. Efferent : X nerve (Observe the symmetry of the palatal contraction)
5) Absent gag reflex : Loss of sensation +/ – motor power (Uvula swings to the normal side due to unopposed action)
Vagus nerve Vagus nerve Reviewed by Radiology Madeeasy on August 08, 2010 Rating: 5
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