2. PARTS OF EXTERNAL EAR
MIDDLE EAR CLEFT
PARTS OF TYMPANIC MEMBRANE
CONTENTS OF MIDDLE EAR
TYMPANIC PLEXUS
TYPES OF MASTOID AND MACEWEN’S
TRIANGLE.
PARTS OF INNER EAR
PATHWAY OF HEARING
3. Parts of the Ear
• Ear can be divided into 3 parts:Ear can be divided into 3 parts:
• External earExternal ear
• Middle earMiddle ear
• Inner earInner ear
4.
5.
6.
7.
8.
9. Layers of TM:
outer epithelial layer
middle fibrous layer
inner mucosal layer
Nerve supply:
Branches of auriculotemporal nerve.
Auricular branch of vagus.
Tympanic branch of glossopharyngeal
nerve.
10.
11.
12.
13.
14.
15.
16. Irregular air filled space within
temporal bone between TM laterally
and osseous labyrinth medially.
Contains- 3 ossicles
2 muscles
chorda tympani
tympanic plexus
3 compartments:
epitympanum
mesotympanum
hypotympanum
17.
18. CHORDA TYMPANI:
Enters the tympanic cavity from the
posterior canaliculus at the junction
of the posterior and lateral wall.
Runs across the medial surface of the
TM.
Pass medial to the upper border of
handle of malleus above the tendon of
tensor tympani continues forward and
leaves by way of anterior canaliculus.
19. TYMPANIC PLEXUS:
Tympanic branch of glossopharyngeal
nerve & carotico tympanic nerves
form a plexus on the promontory.
They provide branches to mucous
membrane lining tympanic cavity, ET,
mastoid antrum and air cells.
20.
21. Anterio inferiorly – Ciliated columnar
epithelium with lot of goblet cells and mucous
glands.
Postero superiorly – Cuboidal epithelium with
less glands.
Epitympanum – Pavement or flat epithelium.
22.
23.
24.
25.
26.
27. Functions of mastoid air cells:
- air reservoir for middle ear.
- insulating chambers, protecting
labyrinth from temperature variation.
- Resonance to sound.
28.
29.
30.
31.
32. Perilymph – similar to extracellular fluid. It
contains more Na+ and less K+. It derived
from CSF.
Endolymph – similar to intracellular fluid. It
contains more K+ and less Na+. It derived
from dark cells of stria vascularis.
Cortilymph – similar to perilymph.
