1. Dr. KarishmaMishra

2. INTRODUCTION
• Eustachian tube also called as
auditory or pharyngotympanic
tube connects nasopharynx with
tympanic cavity.
• In an adult, runs forward,
downward and medially forming a
450 angle with horizontal
• About 36mm in length
• Enters the nasopharynx about
1.25 cm behind the posterior end
of inferior turbinate
• Lined by pseudostratified ciliated
columnar epithelium with goblet
cells in between

3. EMBRYOLOGY
• Develops from tubotympanic
recess, dervied from
endoderm of 1st pharyngeal
pouch
• The distal portion of the
pouch expands and forms
middle ear cavity
• The proximal portion forms
the eustachian tube
• Cartilage and muscles
develop from surrounding
mesoderm

4. PARTS OF EUSTACHIAN TUBE
• It is divided into 2 parts (36 mm)
1) Bony part - Lateral 1/3rd
2)Fibrocartilagenous part - Medial
2/3rd
• The above 2 parts meet at
isthumus which is the narrowest
part of the tube
• The landmarks of the junction of
the cartilaginous ET and bony ET
are the sphenoid spine and
foramen spinosum.

5. CARTILAGENOUS PART
• It is an incomplete cartilagenous
tube
• Superior and medial wall - cartilage
• Inferior and lateral wall - fibrous
membrane
• Lies anteromedially
• 2/3rd of total length i.e 24mm
• Sits in a groove between petrous
temporal bone and greater wing of
sphenoid
• The nasopharyngeal opening is
surrounded by a tubal elevation
above and behind - Torus tubarius

6. On cross section of the medial 2/3rd
part it shows
 Cartilage plate which lies
posteromedially. Crook shaped
with 2 uneven laminae
- Medial lamina - bigger - 5.1mm
- Lateral lamina - smaller - 1.8mm
 An elastin hinge is present at the
junction of these two laminae.
This helps medial laminae to
regain it's original position of
closure
 Ostmann's fat pad (OFP) lies
infero-laterally.
 Helps in closure of ET.
 Disorder of OFP leads Patulous
ET.(seen in rapid weight
loss,pregnancy,aging)

7. BONY PART
• It starts at the anterior wall of the tympanic
cavity and ends at the connection of the
squamous and petrous parts of the temporal
bone
• Lies posterolaterally
• 1/3rd of the total length i.e 12mm
• Formed mainly by petrous temporal bone
• Widest at the tympanic end
• Gradually narrows towards the isthumus
• When following the ET from the
nasopharyngeal orifice to its bony part, the ET
and the carotid artery get closer posteriorly
• The medial wall of the tube is composed of two
parts: a posterior labyrinthine portion and an
anterior carotid portion.27
• the average distance between the
anterosuperior margin of the torus tubarius and
the nearest margin of the internal carotid artery
was 23.5 mm, and even shorter distances were
noted in patients with aberrant carotids

8. • The glenoid fossa of the
temporomandibular joint is lateral
and inferior to the osseous tube, the
middle fossa dura lies superior, and
the internal carotid lies medial.
• The average distance from the
lumen of the tube to the dura of the
middle fossa is 3.6 mm.
Anterior view of the left eustachian tube shows the
shape of the cartilaginous laminae. ICA, Internal carotid artery;
L, air in tubal lumen; LL, lateral cartilaginous lamina; MC, mandibular
condyle; ML, medial cartilaginous lamina; V3, mandibular division,
trigeminal nerve. (Courtesy Michael Teixido, MD, Mads Sorensen, and
Haobing Wang.)

9. MUSCLES
RELATED TO ET
1.TVP (dilator tubae)
2.LVP
3.SPHelps in opening of the tube

10. TENSOR VELI PALATINI
• The tensor has a lateral or superficial
layer originating from the scaphoid fossa
,spine of sphenoid and
• medial or deep layer arising from the
lateral lamina of the tubal cartilage
• Both layers are partly separated by fatty
tissue
• leads around the pterygoid hamulus with
a slim tendon
• Between the tendon of the tensor and the
pterygoid hamulus, there is a small bursa.
• Nerve supply- n.to medial
pterygoid(Mandibular nerve)
• The tensor dilates/opens the Eustachian
tube by drawing the lateral lamina of the
tubal cartilage away from the medial wall

11. LEVATOR VELI PALATINI
• Originates at the lower surface of
the petrous part of the temporal
bone
• Inserts into the soft palate
• Crosses the longitudinal axis of the
Eustachian tube at a groove - tubal
incisure
• Runs inferior and parallel to
cartilagenous part
• Hence pushes it upwards and
medially during contraction thus
assisting in opening the tube.
• Nerve supply- Pharyngeal plexus
• ET dysfunction is seen is cleft
palate as all 3 ms insert in soft
palate. Same in Down syndrome.

12. SALPINGOPHARYNGEUS
• Slender fibre bundle that
originates from the inferior
aspect of the medial lamina of
the Eustachian tube cartilage
• Its lower end inserts into the
posterior wall of the pharynx
• This muscle also helps to open
the tube but it's role is
insignificant

13. LUMEN
• The cross-sectional view through the
lumen shows two different compartments
• The first compartment is a half-
cylindrical space between the medial
and the smaller lateral lamina of the
tubal cartilage - Rüdinger’s safety canal
• Below the safety canal, there is a space
called auxiliary gap
• This gap plays an important role in
clearance and protection due to the
presence of mucosal folds in this gap
• Close to the pharyngeal orifice, there is
a local dilation of the lumen called
Kirchner’s diverticulum .

14. • ARTERIAL SUPPLY
• Br. Of accessory meningeal artery,called tubal artery supplies bony part
• Ascending palatine artery
• Ascending pharyngeal artery
• Middle meningeal artery
• VENOUS DRAINAGE
• Pharyngeal and pterygoid venous plexus
• NERVE SUPPLY
• Tubal mucosa - tympanic branch of glossopharyngeal nerve
• Tensor veli palatini - Mandibular branch of trigeminal nerve
• Levator veli palatini - Pharyngeal plexus
• Salpingopharyngeus - Pharyngeal plexus
• LYMPHATIC DRAINAGE
• Retropharyngeal nodes

15. • Children are more prone to ET dysfunction and OME
than adults

16. ENDOSCOPIC ANATOMY
• Medial end forms a tubal
elevation also called torus
tubarius
• Lymphoid tissue over and
around torus is called
Gerlach's tubal tonsil
• Postero superior to torus is
fossa of Rosenmuller

17. PHYSIOLOGY OF EUSTACHIAN TUBE
• Bony part is always open
• Fibrocartilagenous part is closed at rest
which opens during
- Swallowing
- Yawning
- Sneezing
- Forceful inflation
• Opens actively by contraction of tensor veli
palatini & passively by levator veli
palatini(releases tension on tubal cartilage)
• Closes by elastic recoil of elastin hinge and
deforming force of Ostmann's pad of fat

18. FUNCTIONS OF EUSTACHIAN TUBE
1) VENTILATION AND REGULATION OF MIDDLE EAR
PRESSURE
- For normal hearing, pressure on two sides of the tympanic
membrane must be equal
- Negative or positive pressure in the middle ear affects hearing
- Thus eustachian tube should open periodically to equilibrate air
pressure in middle ear
- Tubal opening is less efficient in recumbent position and during
sleep
- Tubal function is also poor in infants and young children

19. 2) PROTECTIVE FUNCTIONS
A normal eustachian tube protects middle ear from
- Ascending pharyngeal secretions due to the narrow isthumus
and the angulation. Thus reflux occurs more commonly in
patulous ET and in babies
- Pressure fluctuations such as in forceful nose blowing
- Abnormally loud sounds coming from nasopharynx
3) DRAINAGE OF MIDDLE EAR SECRETIONS
- Drainage of secretions into nasopharynx by mucociliary
clearance
- The clearance function is further augmented by active opening
and closing of the tube
4) PREVENTION OF AUTOPHONY

21. EUSTACHIAN TUBE FUNTION TESTS
1) VALSAVA TEST
–passive/non-physiological test
- Principle - Positive pressure in the
nasopharynx causes the air to enter the
eustachian tube.INTACT TM BULGES
- Tympanic membrane perforation hissing
- Fluid in the middle ear cracking sound
- Contraindications
a) Atrophic scar of tympanic membrane
which can rupture
b) Infections of nose and nasopharynx

22. 2) POLITZER TEST
- Done in children who are unable to
perform valsalva
- Olive shaped tip of the politzer's bag is
introduced into the patient's nostril on the
side in which tubal function is to be tested
- Other nostril is closed and the bag is
compressed while at the same time the
patient swallows
- By means of an auscultation tube,
connecting the patient's ear under test to
that of the examiner
- A hissing sound is heard if the tube is
patent
- This test is also used therapeutically to
ventilate the middle ear

23. 3) CATHETERIZATION
- After the nose has been anesthetised,
eustachian tube catheter,the tip of which
is bent is passed along the floor of nose
until nasopharynx
- Here it is rotated 900 medially and then
pulled back till it engages on posterior
border of septum
- It is then rotated 1800 laterally so that
tip lies against tubal opening
- Politzer bag is now connected to
catheter and air is insuflated
- Examiner hears by auscultation tube
put in patient's ear

24. - Blowing sound - Normal ET patency
- Bubbling sound - middle ear fluid
- Whistling sound - Partial ET obstruction
- No sound - Complete ET obstruction
- Complications of ET catheterisation
a) Injury to ET opening
b) Bleeding from nose
c) Transmission of nasal and nasophargeal infections to
middle ear
d) Rupture of atrophic areas of tympanic membrane

25. 4) TOYNBEE TEST
- Uses negative pressure
- Ask the patient to swallow while the nose is
pinched-physiological test
- Draws air from middle ear to nasopharynx -
inward movement of tympanic membrane-
RETRACTION
5) TYMPANOMETRY
- Postive and negative pressures are created
in the EAC and patient swallows repeatedly
- The ability of the patient to equilibrate
positive and negative pressures to ambient
pressure is seen
- Can be done in patients with both intact or
perforated TM

26. 6) RADIOLOGICAL TEST
- A radio opaque dye is instilled into the middle ear
through through a pre existing perforation in TM
and X rays are taken
- This method is obsolete now
7) SACCHARINE OR METHYLENE BLUE TEST
- This method is similar to the radiological test
except that saccharine solution or methylene blue
dye is used
- Time taken by it to reach the pharynx and impart
sweet taste or stain the pharyngeal secretions is a
measure of clearance function
8) SONOTUBOMETRY
- Non invasive technique
- A tone is presented to the nose and it's recording
taken from EAC
- The tone is heard louder when the tube is patent
- Also tells the duration for which the tube remains
open

27. THANK YOU :)