Vagus nerve nuclei & their central connections Nuclei of the vagus nerve 1) Main motor nucleus 1. Receives cortico...
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 nerve5) Absent gag reflex : Loss of sensation +/ – motor power (Uvula swings to the normal side due to unopposed action)
b. Efferent : X nerve (Observe the symmetry of the palatal contraction)
