ANATOMY OF THE
MIDDLE EAR
BY :DINESH V

 Contents of middle ear
 Walls of middle ear
 Mastoid antrum
 The mastoid and its air cell
system
 Developement of mastoid
 Blood supply of middle ear
Overview

MIDDLE EAR :
• The middle ear together with the eustachian tube,
aditus antrum and mastoid air cells is called middle
ear cleft it is lined by mucous membrane and filled
with air.

COMMUNICATION
The middle ear communicates:
Anteriorly with nasopharynx through pharyngotympanic
tube.
Posteriorly with mastoid antrum and mastoid air cells
through aditus to antrum called aditus ad
antrum.

PARTS OF TYMPANIC CAVITY :
MESOTYMPANUM
EPITYMPANUM
HYPOTYMPANUM

The Eustachian tube, tympanic cavity, Attic,
Mastoid air cells develop from the Endoderm of
Tubotympanic recess which arises from the
First Pharyngeal Pouches.

Malleus and Incus are derived from Mesoderm of the First
Arch while the Stapes develop from the Second Arch except
its footplate and annular ligament which are derived from the
ottic capsule.

CONTENTS
• Three small bones called ear ossicles: malleus, incus,
and stapes.
• Two muscles: tensor tympani and stapedius.
• Two nerves: chorda tympani and tympanic plexus.
• Vessels supplying and draining the middle ear.
• Ligaments of the ear ossicles.

INTRA TYMPANIC MUSCLE
• TENSOR TYMPANI: MANDIBULAR NERVE
• STAPEDIUS: FACIAL NERVE

• IT LIES ON PROMONTORY WHICH IS FORMED BY
• 1.TYMPANIC BRANCH OF GLOSSOPHARNGEAL
NERVE
• 2. SYMPATHETIC FIBRES FROM THE PLEXUS
ROUND THE ICA
• IT CARRIES SECRETOMOTOR FIBRES FOR THE
PAROTID GLAND AND IT HAS CLINICAL
CORRELATION :FREYS SYNDROME
TYMPANIC PLEXUS

CHODRA TYMPANI NERVE
• BRANCH OF FACIAL NERVE
• ENTER INTO MIDDLE EAR THROUGH POSTERIOR
CANALICULUS
• IT CARRIES TASTE SENSE FROM 2/3 OF TONGUE
• IT SUPPLIES SECRETOMOTOR FIBRES TO
SUBMAXILLARY AND SUBLINGUAL GLANDS

Boundaries
ROOF:
 FORMED BY TEGMEN TYMPANI
(THIN PLATE OF BONE )
 SEPARATES TYMPANIC CAVITY
FROM THE MIDDLE CRANIAL
FOSSA

FLOOR:
ALSO MADE OF THIN PLATE OF BONE
SEPEARATES TYMPANIC CAVITY FROM JUGULAR
BULB

ANTERIOR WALL:
SEPERATES CAVITY FROM INTERNAL CAROTID ARTERY
TWO OPENING
1. CANAL OF TENSOR TYMPANI MUSCLE
2. EUSTACHIAN TUBE OPENING

POSTERIOR WALL:
• The posterior wall lies close to the
mastoid air cells.
• It presents a bony projection called
pyramid which gives orgin to
stapedius muscle
• Facial nerve runs in facial canal.
• Chorda tympani a branch of facial
nerve, leaves emerges from facial
canal through posterior canaliculus.

MEDIAL WALL:
 PROMONTORY
 OVAL WINDOW IS CLOSED BY FOOTPLATE OF STAPES
 ROUND WINDOW IS CLOSED BY SECONDARY TYMPANIC MEMBRANE
 CANAL FOR FACIAL NERVE PRESENT ABOVE THE OVAL WINDOW
 BONY LATERAL SEMICIRCULAR CANAL
 PROCESSUS COCHLEARIFORMIS

LATERAL WALL :
FORMED LARGELY BY
THE TYMPANIC
MEMBRANE
SEMI TRANSPARENT
MEMBRANE WHICH
FORMS WINDOW OF
MIDDLE EAR

MASTOID ANTRUM
It is a large air-containing space in the
upper part of the mastoid process.
It communicates anteriorly with tympanic
cavity through aditus ad antrum.
Its roof is formed by tegmen antri, which is
the backward continuation of tegmen
tympani.
It separates the antrum from middle cranial
fossa.

MASTOID AND ITS AIR SYSTEM:
Depending on developing of air cells Mastoid is of
following types
1.Well-pneumatized or cellular.-Mastoid cells are well-
developed and intervening septa are thin.
2. Diploetic-Mastoid consists of marrow spaces and a
few air cells.
3. Sclerotic or acellular.-There are no cells or marrow
spaces.

DEVELOPMENT OF MASTOID
• Mastoid develops from the squamous and petrous
bones.
• The petrosquamosal suture may persist as a bony
plate.
• The Korner’s septum, separating superficial
squamosal cells from the deep petrosal cells.

BLOOD SUPPLY OF
MIDDLE EAR:
 6ARTERIES:
2 MAIN;
 ANTERIOR TYMPANIC BRANCH OF MAXILLARY ARTERY – TYMPANIC MEMBRANE
 STYLOMASTOID BRANCH OF POSTERIOR AURICULAR ARTERY –MIDDLE EAR AND MASTOID AIR CELLS
• 4 MINOR
 PETROSAL BRANCH OF MMA
 SUPERIOR TYMPANIC BRANCH OF MMA
 BRANCH OF ARTERY OF PTEYGOID CANAL
 TYMPANIC BRANCH OF ICA

VENOUS AND LYMPHATIC
DRAINAGE:
VEINS DRAIN INTO PTERYGOID VENOUS
PLEXUS AND SUPERIOR PETROSAL SINUS
RETROPHARYNGEAL NODES
PAROTID LYMPH NODES
UPPER DEEP CERVICAL LYMPH NODES

Clinical aspects
• Mastoidits: infection of Mastoid process or the large
bone behind your ear . Middle ear infection cause most
cases of mastoiditis
• Facial nerve palsy: during surgical procedure which
involve middle ear accidental damage to facial nerve
may be caused which leads to facial muscles paralysis
and sometimes loss of taste.

SOURCE
• BOOK- DISEASES OF EAR NOSE
THROAT BY DHINGRA
• TEXT BOOK OF ANATOMY BY
VISHRAM SINGH

THANK YOU