Anatomy of inner ear for #MBBS #BAMS #BDS # BSC #MEDICAL STUDENT . Inner ear in detail

1. ANOTOMY OF INTERNAL EAR
ROLL NO -142,143,144

2. • Internal ear or Labyrinth is an important organ of hearing
& balance.
• It consist BONY & MAMBRANOUS LABYRINTH
• Bony labyrinth –consist of 3 parts
1.VESTIBULE
2.SEMICIRULAR CANAL
3.COCHLEA

3. VESTIBULE
• Central chamber
• On the inner side of medial wall
present 2 resses
1.Spherical recess-lodges saccule
2.Elliptical recess-lodges utrical
Below the elliptical recess opening of
aqueduct of vestibule through which
passes the endolymphtic duct

4. SEMICIRCULAR CANALS
• SUPERIOR SCC- Bulges on the anterior slant of
petrious bone into the base of skull(Arcuate
eminence)
• POSTERIOR SCC- Bulges towards mastoids
• LATERAL SCC-Bulges towards middle ear

5. • Each canal has an ampulated
end which opens into vestibule
• The nonampulated ends of post.
and sup. Canal unite to form a
common channel called crus
commune
These 3 canals open into vestibule by 5 openings.

6. COCHLEA
• Bony cochlea is a coiled tube making 2.5 to
2.75 turns round a central pyramid of bone
called Modiolus
• Around the modiolus a thin plate of bone
called osseous spiral lamina
• Bony cochlea contains 3 compartments.
1.scala vestibuli
2.scala media
3.scala tympani

7. • S. Vestibuli & S. Tympani filled with perilymph
communicate at the apex through
helicotrema.
• Basal coil of cochlea form a bulge on the
medial wall of middle ear.
• S. Vestibuli- Closed by footplate of stapes
• S. Tympani- Closed by secondary TM
• It is also connected with subarachnoid space
through aqueduct of cochlea

8. Membranous labyrinth
● Cochlear duct ( Scala media )
● Utricle
● Saccule
● Semicircular ducts
● Endolymphatic ducts and sacs

10. Cochlear duct
● Also known as membranous
cochlea
● Blind coiled tube, appears
triangular on cross section
● It is connected to Saccule by ductus
reuniens

14. Organ of Corti

15. Saccule
● It lies anterior to Utricle and
opposite to stapes footplate
● It contains macula which is
concerned with linear
acceleration and
deceleration

16. Utricle
● It recieves five opening of
three semicircular ducts
● It contains macula which is
concerned with linear
acceleration and
deceleration

17. Macula

19. Semicircular ducts
● They open in Utricle
● Ampulated end of each
ducts contains crista
ampularis

20. Crista ampularis

22. Endolymphatic ducts and sacs
● It passes through
vestibular aqueduct
● It is exposed for drainage
or shunt meniere’s
disease

23. Inner ear fluid
1. Perilymph
2 . Endolymph

24. Perilymph
It is present b/w bony and
membranous Labyrinth
Formation :
A . It is a filterate of blood serum
B . It is a direct continuation of CSF

25. Endolymph
● It is present in the membranous labyrinth
● It is secreted by secretary cells of
stria vascularis

26. Composition of inner earfluid
and CSF

27. Blood supply
Labyrinth recieves artery supply from labyrinthine artery

31. Venous supply
Venous drainage is through three veins, namely internal
auditory vein, vein of cochlear aqueduct and vein of
vestibular aqueduct, which ultimately drain into inferior
petrosal sinus and lateral venous sinus.