Power point presentation of the middle ear.

1. MIDDLE EAR
SOOREJ JAIBOI K

2. MIDDLE EAR
• Narrow air filled cavity
• Lined by mucous membrane
• Middle ear extends beyond the limits of tympanic membrane and is divided
into
1. Mesotympanum
2. Epitympanum
3. Hypotympanum

4. • Contain 3 auditory ossicles –transmit sound vibration from
tympanic membrane in its lateral wall to the internal ear
Size and shape
• Like a cube
• Compressed from side to side

6. MEASUREMENTS
• VERTIAL DIA - 15MM
• ANTEROPOSTERIOR DIA - 15MM
• TRANSVERSE DIA
• AT THE ROOF - 6MM
• IN THE CENTRE - 2MM
• AT THE FLOOR - 4MM

7. COMMUNICATION
• ANTERIORLY -with nasopharynx
• Posteriorly - with mastoid antrum and mastoid air cells
CONTENTS
• AIR
• OUTSIDE THE MUCOUS LINNING
3 small bone-malleus ,incus , stapes
2 muscles – tensor tympani ,stapedius
2 nerve - chorda tympani and tympanic plexus
Vessel supplying and draining the middle ear
Ligament of the ear ossicle

8. BOUNDARIES
1. ROOF
• Formed by tegmen tympani
• Separates tympanic cavity from middle cranial fossa
• Extend posteriorly to form roof of aditus and antrum
2. FLOOR
• Formed by thin plate of bone
• Separatethe tympanic cavity from jugular bulb
• Tympanic branch of glossopharyngeal nerve pierces the floor b/w jugular fossa and lower opening
of carotid canal

10. ANTERIOR WALL
• Thin plate of bone
• Separate the cavity from internal carotid artery
• Has two opening
1. Upper one for the canal of tensor tmpani muscle
2. Lower one for the Eustachian tube
POSTERIOR WALL
• Separate the tympanic cavity from mastoid antrum and mastoid air cells
• It has the features like

12. ADITUS AD ANTRUM
• Opening in upper part thru which tympanic cavity communicate with mastoid
antrum
2 .PYRAMID – hollow bony projection containing stapedius muscle
3 .VERTICAL PART OF FACIAL CANAL -run in post. Wall just behind the pyramid and
descend upto the stylomastoid foramen
4.Posterior canaliculus for chorda tympani
MEDIAL WALL
• Separate the tympanic cavity from internal ear
• Medial wall presents
1.Oval window 2. round window 3. sinus tympani 4. promontory 5. prominence of
oblique part facial canal 6. prominence of lateral semicircular canal of the internal ear

13. LATERAL WALL
• Formed by tympanic membrane
• Separate the tympanic cavity from the external auditory meatus

15. EAR OSSICLE
MALLEUS
• resemble hammer
• Has head ,neck , handle ,lateral process and anterior process
• Develped from first pharyngeal arch cartilage
• Muscle attached –tensor tympani

16. INCUS
• Anvil
• Developed – first pharyngeal arch cartilage
STAPES
• Stirrup
• Developed – first pharyngeal arch cartilage
•

18. ARTERIAL SUPPLY
1. ANTERIOR TYMPANIC BRANCH OF MAXILLARY ARTERY
2. STYLOMASTOID BRANCH OF POST. AURICULAR ARTERY
3. PETROSAL BRANCH OF MIDDLE MENINGEAL ARTERY
4. SUPERIOR TYMPANIC BRANCH OF MIDDLE MENINGEAL ARTERY
5. ARTERY OF PTERYGOID CANAL
6. TYMPANIC BRANCH OF INTERNAL CAROTID ARTERY

19. VENOUS DRAINAGE
1. Pterygoid venous plexus
2. Superior petrosal sinus

20. LYMPHATIC DRAINAGE
1. Retropharyngeal lymph node
2. Parotid lymph node
3. Upper deep cervical lymph node

21. NERVE SUPPLY
1. Tymphanic branch of glossopharyngeal nerve
2. Sup and inf. Caroticotymphanic nerve
3. Facial nerve
4. Mandibular nerve