Tympanic plexus

The tympanic plexus is a network of nerves located in the middle ear. It plays a crucial role in the innervation of the tympanic cavity and the mucous membrane of the middle ear. This plexus is primarily formed by the tympanic nerve, a branch of the glossopharyngeal nerve (cranial nerve IX), and receives contributions from the carotid plexus.

Anatomy

The tympanic plexus is situated on the promontory of the middle ear, which is a rounded eminence on the medial wall of the tympanic cavity. The plexus is formed by the tympanic nerve, which enters the middle ear through the tympanic canaliculus. This nerve carries both sensory and parasympathetic fibers.

Components

• Tympanic nerve: A branch of the glossopharyngeal nerve, it enters the middle ear and forms the tympanic plexus on the promontory.
• Carotid plexus: Sympathetic fibers from the carotid plexus join the tympanic plexus, contributing to its formation.

Branches

The tympanic plexus gives rise to several branches that supply the mucous membrane of the middle ear, the mastoid air cells, and the auditory tube. One of the significant branches is the lesser petrosal nerve, which carries parasympathetic fibers to the otic ganglion.

Function

The primary function of the tympanic plexus is to provide sensory innervation to the mucous membrane of the middle ear. It also supplies parasympathetic fibers to the parotid gland via the lesser petrosal nerve and the otic ganglion. The sympathetic fibers from the carotid plexus are involved in vasomotor control.

Clinical significance

Disorders of the tympanic plexus can lead to various symptoms, including ear pain and dysfunction of the parotid gland. Infections or inflammations of the middle ear, such as otitis media, can affect the tympanic plexus, leading to referred pain or altered sensation.

Images

Diagram of the tympanic plexus on the promontory of the middle ear.

The course of the glossopharyngeal nerve, showing its branches including the tympanic nerve.

Related pages

• Middle ear
• Glossopharyngeal nerve
• Otic ganglion
• Lesser petrosal nerve