Corpus: Jacobson's anastomosis

The term Jacobson's anastomosis refers to the nerve fibre connection between the glossopharyngeal nerve (IX nerve) and the parotid gland (glandula parotidea). It contains parasympathetic, general visceromotor nerve fibres that originate from the nucleus salivatorius inferior and are responsible for the secretory supply of the parotid gland.

The definition of Jacobson's anastomosis is not standardised in the anatomical literature. Sometimes the term is used only for the postganglionic fibres between the otic ganglion and the parotid gland.

Parasympathetic fibres run from the nucleus salivatorius inferior in the medulla oblongata via the glossopharyngeal nerve over the jugular foramen to the extracranial. Here they leave the inferior ganglion unconnected and reach the middle ear with the tympanic nerve via the tympanic canal.

In the middle ear, the fibres form the tympanic plexus, into which sympathetic fibres of the carotid tympanic nerves are taken up from the internal carotid plexus. The parasympathetic fibres continue through the middle cranial fossa as the petrosal nerve before leaving it again through the sphenopetrous fissure and reaching the infratemporal fossa to the otic ganglion.

The fibres are connected to the 2nd neuron in the otic ganglion. The postganglionic fibres are then transferred via a ramus communicans cum nervo auriculotemporali to the auriculotemporal nerve, a branch of the mandibular nerve. This finally supplies the parotid gland via its parotid rami.

In some cases, it is possible that the parasympathetic fibres do not reach the parotid gland directly, but via a further diversion. In this case, the parasympathetic fibres are transmitted to the facial nerve via a ramus communicans cum nervo faciali and reach the parotid gland through the parotid plexus formed by it. The auriculotemporal nerve runs through the parotid plexus, which means that anatomical descriptions vary.

Damage to the parasympathetic fibres of the Jacobson anastomosis can be caused by surgical interventions in the infratemporal fossa or in the area of the middle ear, skull base fractures or tumours. It leads to a reduction in saliva secretion with resulting xerostomia.