9. A} VESTIBULE
Central chamber
Lateral wall : oval window
Spherical- lodges saccule
Medial wall : 2 Recessess
Elliptical- lodges utricle
Spherical R. – has perforated holes
Maculae Cribrosa Media –
inferior vestibular nerve
Elliptical R. –
Maculae Cribrosa Superior (Mike’s spot)
– “Translabyrinthe” approach
N to Utricle & ampulla
10.
11. B} SEMI CIRCULAR CANALS
Lie At
to each other
Rt
Superior
(15-20mm)
Angles
lateral
(12-15mm)
Posterior
(18-20mm)
lie
lie
transverse
to petrous part of
Temporal bone
Parallel to petrous part of
temporal bone
bulge into aditus & antrum
12. Ampullated end-opens into vestibule
Non Ampullated end of Supr & Post’r canals
Unite – common channel –
CRUS COMMUNE(4MM)
C}
COCHLEA
Snail
Lies Antr to bony labyrinth
L=30mm
Coiled tube
2.5 - 2.75 turns around central pyramid of bone
MODILOUS – spirally –OSSEOUS SPIRAL
LAMINA
13. base towards Int. Acoustic Meatus
transmits cochlear vessels & nerves
•
Bony cochlea : 3
compartments
Scala Vestibuli
Scala Tympani
Scala media
(Membranous cochlea)
-
perilymph
- communicate via cochlea apex
HELICOTREMA
Endolymph
21. Basilar memb
– supports organ of corti - has sound receptors
- thin inner part ZONA ARCUATA
- thick outer part ZONA PECTINATA
- seperates Scala tympani from scala media
-its length from Basal coil (High freq sound) – Apical coil (low freq
sound)
Reissner’s membrane
Seperates scala vestibuli - scala media
Stria vascularis
-Vascular epith.
-Endolymph secretion
Cochlear duct connects to saccule by DUCTUS REUNIENS
22. Organ
of
corti
• Spead entirely over Basilar memb
Has TUNNEL OF CORTI – consists of 2 rows of rods of inner & outer hair
cells
1 row of inner hair cells & 3-4 rows of outer hair cells
Inner rods-3500
Outer rods-12000
Hair cells supported by Pillar cells , Dieter cells , Hensens cells
Mechanical sound energy gets
transduced into electrochemical
energy
23. TECTORIAL MEMBRANE
• Has gelatinous matrix with fibers
• Lies above Organ of corti
• Its undersurface attaches to tip of outer hair cells
Shearing force b/w them stimulates hair cells
24. UTRICLE & SACCULE
Both lie in bony vestibule but saccule lies anterior to utricle
Utricule connects to saccule via
UTRICOSACCULAR DUCT
Cochlear duct connects to saccule via DUCTUS REUNIENS
Utricle has 5 openings of 3 semicircular canals
Spherical recess-Saccule (S-S)
Elleptical recess-Utricle
U – lies horizontally
Its vestibular receptor organ MACULA
S- lies vertically
Linear acceleration & decelaration
Has hair cells + supporting cells + gelatinous mass
secreted by
has
Mucopolysaccharides
26. ENDOLYMPHATIC DUCT & SAC
• Union of 2 ducts (1 from saccule and 1 from utricle)
• Pass through Vestibular Aqueduct
• Terminal end – dilated – forms ENDOLYMPHATIC SAC
27.
28. SEMICIRCULAR DUCTS
3 in number
Open in utricle
Ampullated end – has thick neuroepithelium – CRISTA AMPULLARIS
Hair cells + Supporting cells + Gelatinous mass
dome shaped In cristae
CUPULA
29.
30. HAIR CELLS
2 types
type 1
(FLASK SHAPED)
Summit
Hair cells
type 2
(CYLINDRICAL)
CRISTAE
1 KINOCILIUM
Periphery
Many STEREOCILIA (60-110)
32. MECHANISM
OF
HEARING
TM
SOUND
PINNA
AUDITORY N.
EAC
Vibration of
TRANSDUCTION
Pr. Changes in
OSSICULAR CHAIN
FOOT PLATE
OF STAPES
LABYRINTHINE
FLUID
STIMULATES HAIR CELLS OF
BASILAR MEMB.MOVES
ORGAN OF CORTI
COCHLEAR NUCLEI - SUPR. OLIVARY COMPLEX – LAT. LEMNISCUS – INFR. COLLICULUS
AUDITORY CORTEX
(AREA 41 / BROADMANN’S AREA)
MEDIAL GENICULATE BODY