Nerves - Parasympathetic Innervation Flashcards
What are the four parasympthatic ganglia of the head?
1) Ciliary
2) Otic
3) Pterygopalatine
4) Sub-mandibular
Ciliary ganglion
Location - anterior to superior orbital fissure, between the rectus muscle and optic nerve.
Pre-ganglionic fibres - supplied by Edinger-Westphal nucleus
Post-ganglionic fibres - leaves via the short ciliary nerve - innervates structures in the eye.
Target organs - sphincter pupillae and the ciliary muscles
In addition, two sets of nerves pass through the ganglion, without synapsing:
1) sympathetic nerves from the internal carotid plexus
2) sensory fibres from the nasociliary nerve - cornea, ciliary body, iris
Pterygopalatine ganglion
Location - pterygopalatine fossa
Preganglionic fibres - superior salivatory nucleus - greater petrosal nerve
Post-ganglionic fibres - leaves ganglion by hitchiking onto the maxillary nerve
Target organs - lacrimal gland, mucous glands of the nasal cavity, nasopharynx and palate.
Sympathetic fibres from the IC plexus and sensory fibres from the maxillary nerve pass through ganglion without synapsing.
Submandibular ganglion
Location - inferior to the lingual nerve
Pre-ganglionic fibres - superior salivatory nucleus - carried with the chorda tympani - hitch-hikes along lingual nerve to ganglion.
Post-ganglionic fibres and target organs - directly to sub-lingual and sub-mandibular glands.
Sympathetic fibres from the facial artery plexus pass through the ganglion.
Otic ganglion
Location - inferior to foramen ovale in the infratemporal fossa. Medial to the mandibular branch of the trigeminal nerve.
Preganglionic fibres - inferior salivatory nucleus (CN IX) - fibres are found in the lesser petrosal nerve, to reach the otic ganglion.
Post-ganglionic fibres and target organ - parasympathetic fibres hitch-hike along the auriculotemporal fibres to provide secretomotor function to the parotid gland.
Sympathetic fibres from the superior cervical chain pass through otic ganglion. They travel with the middle meningeal artery to innervate the parotid gland.
Clinical relevance - Adie’s pupil
Ciliary ganglion provides innervation to the sphincter pupillae muscle, which acts to constrict the pupil.
If there is damage to the ganglion, there is a loss of innervation to the sphincter pupillae.
This results in a permanently dilated pupil that doesn’t constrict in the presence of light.
Aetiology - thought to be due to inflammation from viral or bacterial infection.
