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Jacobson Nerve

nervus tympanicus Jacobsoni

Jacobson nerve (tympanic nerve) is a branch of the glossopharyngeal nerve (CN IX) arising from the inferior ganglion and re-entering the skull through the inferior tympanic canaliculus to reach the middle ear. It contributes parasympathetic preganglionic fibres (via the lesser petrosal nerve) to the parotid gland and provides sensory innervation to the middle ear mucosa via the tympanic plexus on the cochlear promontory.

Region: Head & Skull

Clinical Relevance

Clinical Notes

Jacobson nerve is the nerve of origin of glomus tympanicum paraganglioma, the most common benign middle ear tumour. Paraganglionic tissue associated with the tympanic plexus on the cochlear promontory undergoes neoplastic transformation, producing a vascular red pulsatile mass behind the tympanic membrane that causes pulsatile tinnitus and conductive hearing loss. Small glomus tympanicum tumours are removed through a transcanal approach with direct visualisation of the cochlear promontory; all bleeding points are the tympanic vessels from Jacobson nerve.

Pathology

Common Injuries & Conditions

Glomus Tympanicum Arising from Jacobson Nerve

Paraganglioma arising from the tympanic plexus of Jacobson nerve on the cochlear promontory produces a vascular pulsatile middle ear mass visible through the tympanic membrane causing pulsatile tinnitus and conductive hearing loss, resected by transcanal tympanotomy with bipolar coagulation of the tympanic plexus vessels.