- 1) Nuclei of vagus
- 2) Ganglia & Branches of Vagus
- 3) Supply of Vagus
NUCLEI
Are present in Medulla Oblongata (lower most part of Brain Stem)
They are in the vicinity of Dorsal Respiratory nucleus.
- Nucleus Ambiguus
- Dorsal nucleus of Vagus
- Tractus Solitarius
- Upper part of Spinal nucleus of Trigeminal
- Nucleus Ambiguus- gives rise to Special Visceral Efferent ( SVE) fibres which supply to muscles of pharynx, larynx & soft palate.
- Dorsal nucleus- gives rise to General Visceral Efferent (GVE) fibres which supply Para sympathetic innervation to heart, bronchi & gastrointestinal tract. These fibres are preganglionic ending in postganglions situated near viscera or in the walls of viscera. They innervate smooth muscles & glands of viscera.
- Nucleus Solitarius – Receives Special Visceral Afferent (SVA) fibres For Taste from posterior most part of tongue & epiglottis.It also receives General Visceral Afferent (GVA) fibres from pharynx ,larynx, trachea ,thoracic wall, oesophagus & thorasic & abdominal viscera
- Upper part of Spinal nucleus of Trigeminal – Receives General Somatic Afferent ( GSA) fibres From skin of auricle.
GANGLIA & BRANCHES
- Superior
- Inferior
- Superior ganglion – gives
- Meningeal branch supplying dura matter in the region
- Auricular branch supplying posterior wall & floor of external acoustic meatus
- Inferior ganglion – gives
- Pharyngeal branch dividing into numerous branches to form a plexus. These supply to muscles of pharynx & soft palate.( The pharyngeal plexus is joined by branches of Glassopharyngeal nerve & branches from Sympathetic trunk)
- Carotid body branches ( responsible for Baroreceptor buffer reflex of arterial pressure)
- Superior Laryngeal nerve ends by dividing into internal & external laryngeal nerve. Internal laryngeal nerve is sensory, carries the sensory signals from posteriormost part of tongue, pharynx, epiglottis & mucus membrane of upper part of larynx.( upto vocal folds)External laryngeal nerve is motor supplies crick thyroid muscle.
- Recurrent laryngeal nerve course is different on right & left side. It has sensory & motor fibres. Sensory fibres supply to lower half of larynx, trachea, oesophagus. It gives branches to cardiac plexus. Motor fibres supply to all intrinsic muscles of larynx ( except cricothyroid)
Cardiac branches– Each Vagus nerve gives one or more Superior Cervical Cardiac branch( in upper neck),Inferior Cervical Cardiac branch ( in lower neck),additional branches from its mediastinal part & from Recurrent laryngeal…..all together end in superficial & deep Cardiac plexus.