The Four Parasympathetic Ganglia and Their Associated Cranial Nerves
The four parasympathetic ganglia are the ciliary ganglion (CN III), pterygopalatine ganglion (CN VII), otic ganglion (CN IX), and submandibular ganglion (CN VII). 1
Detailed Anatomy of Each Ganglion
1. Ciliary Ganglion
- Associated with the oculomotor nerve (CN III) 1, 2
- Located deeply in the orbit, laterally to the optic nerve 1
- Contains abundant tyrosine hydroxylase (TH)-positive neurons, which are more numerous than neuronal nitric oxide synthase (nNOS)-positive neurons 3
- Provides parasympathetic innervation to the eye, controlling pupillary constriction and accommodation 2
2. Pterygopalatine Ganglion
- Associated with the facial nerve (CN VII) 1, 2
- Located in the pterygopalatine fossa 1
- Contains few or no TH-positive neurons 3
- Provides parasympathetic innervation to the lacrimal gland and nasal mucosa 2
- Shows variations in the number and volume of fiber bundles connected to it 1
3. Otic Ganglion
- Associated with the glossopharyngeal nerve (CN IX) 1, 2
- Located medially to the mandibular nerve, right beneath the oval foramen 1
- Contains few or no TH-positive neurons 3
- Shows variations regarding its proximity to the mandibular nerve 1
- Provides parasympathetic innervation to the parotid gland 2
4. Submandibular Ganglion
- Associated with the facial nerve (CN VII) 1, 2
- Located laterally to the hyoglossus muscle, below the lingual nerve 1
- Contains abundant TH-positive neurons and extremely strong nNOS immunoreactivity 3
- Provides parasympathetic innervation to the submandibular and sublingual salivary glands 2
- Shows variations in the number and volume of fiber bundles connected to it 1
Clinical and Developmental Significance
- These ganglia develop through sequential actions of growth factors, with GDNF required early for proliferation and/or migration of neuronal precursors, followed by neurturin for further development and maintenance 4
- Most parasympathetic neurons arise from bi-potent progenitors that generate both glia and neurons, originating from nerve-associated Schwann cell precursors rather than neural crest cells 2
- Significant individual variations exist in the density of autonomic markers in these ganglia, suggesting differences in sensitivity to medicines affecting autonomic nerve function 3
- The detailed anatomy of these ganglia and their roots is crucial for safe cranial surgery and interventions in the maxillofacial region, skull base, and orbit 5
Anatomical Variations
- While the location of these ganglia remains relatively consistent, morphological variations have been observed 1
- Variations exist in the proximity of the otic ganglion to the mandibular nerve 1
- The number and volume of fiber bundles connected to the submandibular, otic, and pterygopalatine ganglia can vary between individuals 1
- The traditional dichotomy between sympathetic and parasympathetic function is not always clear-cut in human cranial autonomic ganglia 3