Corpus: Tympanic cavity

In veterinary medicine, the term cavum tympani refers to the central cavity in the pars tympanica of the temporal bone (os temporale), which also contains the auditory ossicles (ossicula auditus).

Components[Bearbeiten]

The tympanic cavity can be divided into three sections:

• Epitympanicum: located dorsally
• Mesotympanicum: the middle and largest part
• Hypotympanicum: corresponds approximately to the bulla tympanica

Morphology[Bearbeiten]

Most of the wall of the cavum tympani is formed by the pars tympanica of the temporal bone, only the medial wall belongs to the pars petrosa.

Various wall sections can be differentiated within the tympanic cavity:

• Paries tegmentalis: forms the roof
• Paries labyrinthicus: medial wall, the inner ear labyrinth is connected here with the middle ear (auris media)
• Paries mastoideus: posterior wall
• Paries tubarius: anterior wall, the auditory tube opens into the tympanic cavity here
• Paries membranaceus: lateral wall, formed almost exclusively by the tympanic membrane (membrana tympani)

The medial wall (paries labyrinthicus) is perforated by two openings:

• Atrial window (oval window, Fenestra vestibuli sive ovalis): is closed by the stapes plate
• Snail window (round window, fenestra cochleae sive rotunda): is closed by the secondary tympanic membrane (membrana tympani secundaria)

The tympanic opening of the eustachian tube, the ostium tympanicum tubae auditivae, is located on the anterior wall (paries tubarius). This opening connects the cavum tympani with the pharyngeal cavity (cavum pharyngis) and thus with the outside world.

The floor and a large part of the side wall is formed by the bulla tympanica, which embodies the hypotympanicum. The bulla tympanica is a thin-walled bone bladder that is formed differently in different animal species.

The cavum tympani is lined by a delicate mucous membrane, which is largely covered by monolayer squamous epithelium, but also partly by ciliated epithelium. The ossicles and their muscles are also covered by this mucous membrane.

• Salomon FV, Geyer H, Uwe G. 2008. anatomy for veterinary medicine. 2nd, updated and expanded edition. Stuttgart: Enke Verlag in MVS Medizinverlage Stuttgart GmbH & Co. KG. ISBN: 978-3-8304-1075-1
• Nickel R, Schummer A, Seiferle E. 2003. Textbook of Anatomy of Domestic Animals, Volume IV: Nervous System. 4th, unchanged edition. Stuttgart: Parey in MSV Medizinverlage Stuttgart GmbH & Co. KG. ISBN: 978-3-8304-4150-2