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Vestibulocochlear
Organ ---SHANDONG UNIVERSITY
Liu Zhiyu
The Vestibulocochlear Organ
Parts:
external ear
middle ear
internal ear
Conduct the sound wave。
Contains the receptors of auditory
and vestibular organs
External ear
The external ear consists of
auricle
external acoustic meatus
tympanic membrane
External ear
1. Auricle
Helix
Antihelix
crura of antihelix
triangular fossa
Scapha
auricular concha
externalacoustic pore
Tragus
Antitragus
auricular lobule
External ear
2. external acoustic meatus :
bony part ：medial 2/3
cartilaginous part ：lateral 1/3
External ear
3. tympanic membrane :
Flaccid part : upper 1/4
Tense part : lower 3/4
Umbo of tympanic membrance
鼓膜脐
Cone of light
Middle ear
Consists of three parts
 Tympanic cavity
 Auditory tube
 Mastoid antrum and mastoid cells
Tympanic cavity
 Position: An irregular air-filled cavity locates within the temporal
bone, and lies between the tympanic membrane and the lateral wall of
the inner ear.
• It contains the auditory ossicles, ligaments, muscles, vessels and
nerves.
Middle ear
 Boundaries:
(1) Roof or tegmental wall :
(2) inferior wall or jugular wall: separates the cavity from
superior bulb of internal jugular v.
Tympanic cavity
(3) Anterior wall or carotid wall:
Upper opening for tensor tympani m.
lower opening for auditory tube
(4) Posterior wall or mastoid wall:
Aditus of mastoid antrum:
Pyramidal eminence
Middle ear
(5) lateral wall or membranous wall:is formed by
tympanic membrane
epitympanic recess
Middle ear
(6) Medial wall or labyrinthine wall :
promontory
Fenestra vestibuli
Fenestra cochleae: covered by secondary tympanic membrane
Prominence of facial canal
Middle ear
2. Aditory tube :
Bony part : posterolateral 1/3 ,open into the anterior wall of
tympanic cavity
Cartilaginous part : anteromedial 2/3, open into the nasopharynx
In childhood:
shorter, wider and
more horizontal than
in adult
Middle ear
3. Mastoid antrumand mastoid cells
mastoid cells
Middle ear
2）content of tympanic cavity
(1)auditory ossicles：
malleus
incus
stapes
（2）
tensor tympani
stapedius
Internal ear
Position: lies in the petrous part of the temporal bone,
and consists of two parts:
bony labyrinth
membranous labyrinth
Internal ear
The bony labyrinth is composed of the compact bone, and the
latter, a series of communicating membranous sacs and
ducts, is contained within the bone labyrinth.
The membranous labyrinth is
filled with endolymph,
The space between the
membrnous and bony labyrinth
is filled with perilymph.
bony labyrinth
Cochlea
Vestibule
Bony semicircular canals
bony labyrinth
(1) Cochlea:
Cochlear spiral canal
Modiolus
Osseous spiral lamina
Scala vestibuli
Scala tympani
Scala vestibuli
Scala tympani
Modiolus
bony labyrinth
(2) Vestibule:
is the central part of bony labyrinth，and is
medial to the tympanic cavity，it has 4 walls
On its lateral wall
fenestra vestibuli
fenestra cochleae.
The medial wall is the fundus of
the internal acoustic meatus
bony labyrinth
(2) Vestibule:
On the posterior wall
5 opennings of emicircular
canals.
On its anterior wall,
a large opening
communicates with the
scale vestibuli of
cochlea.
bony labyrinth
(3) Bony semicircular canals:
three in number, the ant., post., and lateral
simple bony crus
ampullar bony crura
bony ampulla
common bony crus
Posterior
semicircular canal
Lateral semicircular
canal
Anterior semicircular
canal
2. Membranous labyrinth
(1) Cochlear duct : in cochlear spiral canal
(2) Utricle and saccule: in vestibule
(3) Semicircular ducts :
2. Membranous
labyrinth
labyrinth 膜迷路
(1) Cochlear duct :
superior wall : vestibular wall
inferior wall : tympanic wall or basilar membrane
spiral organ （Corti ）
lateral wall:
Membranous labyrinth
(2) Utricle and saccule :
Connected to each other by utriclosaccular duct
receptors of balance, respond to
macular utricli
linear acceleration and deceleration
macular sacculi
Semicircular ducts
Cochlear duct
saccule
Utricle
Membranous labyrinth
(3) Semicircular ducts :
membranous ampullae
crista ampullaris ：
receptor of balance, which respond
to rotation of the head
The Vestibulocochlear Organ
Internal acoustic meatus
structures passing through it
Facial nerve
vestibulocochlear nerve
vessels of labyrinth
The position of internal ear
Conduction of sound
1、 Air conductive pathway：
the sound wave
the external acoustic meatus
tympanic membrane
fenestra vestibuli
chain of auditory ossicles
perilymph within the scala vestibuli
endolymph within cochlear duct
nerve impulse
vestibulocochlear n.
spiral organ
brain
The summary
Bony labyrinth:
Membranous
Abyrinth ：
Bony semicircular
canals
Semicircular ducts
Receptors： crista ampullaris
Vestibule
Utricle、saccule
Macular
utricli
Receptors of balance
Macular
sacculi
Cochlea
Cochlear duct
spiral organ
Receptor of hearing
前庭阶
鼓阶
Cochlear n.
Facial n.
Veastibular n.
Fenestra vestibuli
Prominence of
facial canal
Pyramidal eminence
Promontory
Fenestra
cochleae
Conduction of sound
External
ear
Tympanic
membrane
chain of
auditory
ossicles
fenestra
vestibuli
Internal
ear
spiral
organ
cochlear
n.