Otic Ganglion — Relations to Mandibular Nerve
Location
- Small parasympathetic ganglion situated in the infratemporal fossa
- Lies immediately below the foramen ovale
- Medial to the mandibular nerve (V3)
- Lateral to the cartilaginous part of the auditory (Eustachian) tube
- On the medial surface of the mandibular nerve trunk
Roots (Functional Components)
| Root | Origin | Fibres | Function |
|---|---|---|---|
| Parasympathetic (preganglionic) — functional root | Lesser petrosal nerve (branch of glossopharyngeal, CN IX, via tympanic branch → tympanic plexus → lesser petrosal nerve) | GVE preganglionic parasympathetic | Synapse in ganglion → postganglionic to parotid |
| Sympathetic | Plexus on middle meningeal artery (from superior cervical ganglion) | GVE postganglionic sympathetic | Pass through without synapse → vasomotor to parotid |
| Sensory | Auriculotemporal nerve (V3) | GSA | Pass through without synapse |
| Motor | Nerve to medial pterygoid (V3) | SVE | Pass through without synapse → tensor tympani, tensor veli palatini |
Only the parasympathetic fibres synapse in the otic ganglion. Sympathetic, sensory, and motor fibres pass through without relay.
Distribution
- Postganglionic parasympathetic fibres travel with the auriculotemporal nerve (V3) to reach the parotid gland
- These fibres provide secretomotor supply (saliva production) to the parotid
Pathway Summary
CN IX → Jacobson's nerve (tympanic branch) → tympanic plexus
→ Lesser petrosal nerve → foramen ovale / foramen of Arnold
→ Otic ganglion (synapse)
→ Postganglionic fibres join auriculotemporal nerve
→ Parotid gland (secretomotor)
Mnemonic
“Oro = Otic” — the Otic ganglion supplies the Oral/parotid gland (From Medinaz parasympathetic ganglia: Oro = Otic, Cranial = Ciliary, Para = Pterygopalatine, Sympathetic = Submandibular)
Clinical Significance
Frey’s Syndrome (Auriculotemporal Nerve Syndrome):
- Follows parotidectomy or injury to the auriculotemporal nerve
- Regenerating parasympathetic secretomotor fibres from the otic ganglion aberrantly reinnervate the sweat glands of the overlying skin
- Result: Gustatory sweating — flushing and sweating over the cheek during eating
- Treatment: Tympanic neurectomy (cuts preganglionic at tympanic plexus); Botulinum toxin injection
Parotid Tumour Surgery:
- Preservation of otic ganglion pathway important; damage → loss of parotid secretion
Mandibular Nerve | Branches of Mandibular Nerve — Posterior Division