Superior and inferior salivatory nuclei (CN VII and IX)
Preganglionic · CN VII (SSN, pons) CN IX (ISN, medulla)
The superior salivatory nucleus in the pons sends preganglionic fibres out in the nervus intermedius of CN VII, splitting at the geniculate ganglion into the greater petrosal nerve (to pterygopalatine ganglion) and chorda tympani (to submandibular ganglion). The inferior salivatory nucleus in the medulla sends fibres in CN IX via the tympanic nerve and lesser petrosal nerve to the otic ganglion.
Traced from the start
- Parasympathetic (craniosacral) outflow
- Superior and inferior salivatory nuclei (CN VII and IX)
Detail
- Superior salivatory nucleus
- Pons → nervus intermedius → geniculate ganglion → greater petrosal nerve (lacrimal, nasal, palatine glands) and chorda tympani (submandibular, sublingual glands)
- Inferior salivatory nucleus
- Medulla → CN IX → tympanic nerve of Jacobson → tympanic plexus → lesser petrosal nerve → foramen ovale → otic ganglion (parotid)
- Chorda tympani also carries
- Taste from the anterior two-thirds of the tongue — lost with the salivary fibres
When it goes wrong
Facial nerve lesion at or proximal to the geniculate ganglion (Bell palsy, temporal bone fracture, cerebellopontine angle tumour)
Lower motor neurone facial weakness plus reduced tearing, loss of taste on the anterior two-thirds of the tongue and hyperacusis — the extra features localise the lesion above the stapedius branch
Facial nerve lesion in the facial canal distal to the geniculate ganglion but proximal to chorda tympani
Facial weakness with loss of taste and reduced submandibular salivation, but lacrimation preserved because the greater petrosal nerve has already left
Practise this structure
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