Lacrimal, nasal and salivary glands
Target & receptor · M3 watery α1 / β viscous
Parasympathetic M3 stimulation (with VIP-mediated vasodilatation) produces copious watery secretion; sympathetic fibres from the superior cervical ganglion produce a small volume of viscous protein-rich saliva and constrict gland vessels. Unusually, both divisions stimulate secretion — they differ in volume and composition.
Traced from the start
- Parasympathetic (craniosacral) outflow
- Superior and inferior salivatory nuclei (CN VII and IX)
- Pterygopalatine (sphenopalatine) ganglionSubmandibular ganglionOtic ganglion
- Sympathetic (thoracolumbar) outflow
- Intermediolateral cell column T1–L2 via white rami communicantes
- Superior cervical ganglion
- Secretomotor fibres carried on trigeminal branchesInternal and external carotid plexuses (oculosympathetic pathway)
- Lacrimal, nasal and salivary glands
Detail
- Parasympathetic
- M3 → high-volume, low-protein saliva and tears; cholinergic vasodilatation increases gland blood flow
- Sympathetic
- α1 vasoconstriction and β1 amylase-rich thick saliva — the dry, sticky mouth of anxiety
- Daily output
- About 1–1.5 L of saliva; submandibular glands contribute most at rest, parotid on stimulation
When it goes wrong
Antimuscarinic drugs — tricyclics, oxybutynin, hyoscine, antipsychotics, antihistamines
Dry mouth, dry eyes and blurred vision; the same effect is exploited with hyoscine or glycopyrrolate for drooling and end-of-life secretions
Cholinesterase inhibitors (organophosphates, neostigmine overdose)
Drooling, tearing and rhinorrhoea as part of the cholinergic crisis, alongside bronchorrhoea and bradycardia
Practise this structure
1 question in the bank tagged Autonomic.