Inner ear

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Location and main components of the inner ear in humans
Schematic drawing of the right inner ear:
1 vestibular nerve
2 cochlear nerve
3 facial nerve
4 outer facial knee with equiv. geniculi
5 chorda tympani
6 cochlea
7 semicircular canals
8 hammer handle
9 eardrum
10 eustachian tube
Section through the left temporal bone (os temporale) of the human being (front-left view):
1 = Pars squamosa (temporal bone scale)
2 = Spina suprameatalis (cusp behind the auditory canal)
3 = Meatus acousticus externus ( outer auditory canal )
4 = Pars tympanica ( Tympanic part)
5 = mastoid process (mastoid process)
6 = fenestra vestibuli ovalis (oval window)
7 = promontory (cusp between oval and round window)
8 = fenestra cochleae rotunda (round window)
9 = eminentia pyramidalis (attachment for the stapedius muscle - black represented the course of the chord)
10 = Apertura tympanic canaliculi chordae tympani (opening for the tympanic string - a branch of the VII cranial nerve ; the tympanic string extends disclosed herein through the air-filled middle ear cavity)
11 = sulcus tympanicus (bone channel for the ear drum )
12 = aditus ad antrum (Opening to the mastoid antrum - a cavity in the mastoid process)
13 = Canalis nervi facialis (incised canal of the VII cranial nerve)
14 = Cochlea (Schnec ke)

In addition to the middle and outer ear, the inner ear ( auris interna ) is a part of the ear in vertebrates . In mammals, it consists of the cochlea ( Latin cochlea ) and the organ of equilibrium .

construction

The inner ear is a complex shaped cavity in the temporal bone , which is known as the bony labyrinth ( Labyrinthus osseus ). It is surrounded by a bone material that is the hardest material in the human body after tooth enamel. The cavity is filled with the membranous or membranous labyrinth (lat. Labyrinthus membranaceus ). This contains a system of canals and chambers with a fluid called perilymph . In this fluid-filled system, a thin-walled second canal system is embedded that is filled with endolymph .

The inner ear, more precisely the perilymphatic space, has two openings towards the middle ear. The “oval window” ( Fenestra vestibuli , syn. Fenestra ovalis) is closed by the footplate of the stapes and is the coupling point of the ossicular chain where the vibrations triggered by sound waves are transmitted to the inner ear. The second opening is the "round window" ( Fenestra cochleae ), which is closed by a movable membrane ( Membrana tympani secundaria ) and enables a compensation for the pressure fluctuations imported through the oval window (stirrup).

The inner ear has three openings to the cranial cavity . On the one hand, the internal auditory canal , which forms the point of passage for the facial nerve , the vestibulocochlear nerve and blood vessels. Furthermore, the very narrow vestibular aqueduct , which contains the endolymphatic duct , which begins at the utriculus and sacculus (parts of the endolymphatic space) and whose blind sack-like end is located on the back of the temporal pyramid between two sheets of the dura mater . Finally, the perilymphatic space of the inner ear has an equally close connection to the interior of the skull, the canaliculus cochleae , through which the perilymphatic duct runs. This reaches the posterior fossa on the underside of the petrous pyramid.

Diseases

See also

Individual evidence

  1. ↑ Alexander Berghaus , Gerhard Rettinger, Gerhard Böhme: ear, nose and throat medicine . Hippokrates, Stuttgart 1996, ISBN 3-7773-0944-3 , A ear, 1 anatomy, 1.3 inner ear, p. 29–30 ( docplayer.org [accessed June 3, 2020]).
  2. ^ Neil A. Campbell , Jane B. Reece : Biology . Spectrum, Heidelberg / Berlin 2003, ISBN 3-8274-1352-4 , p. 1277-1281 .