Anatomy and Physiology
of the Eustachian Tube
Dr. Krishna Koirala

• Links the pharynx to the middle ear
• Eustachius (1562) : Pharyngotympanic tube
• Antonio Valsalva : Eustachian tube
• Develops from tubotympanic recess which is derived from
endoderm of 1st pharyngeal pouch
• 36 mm long in adults
• Directed anteriorly, inferiorly and medially from anterior wall of
middle ear forming an angle of 450 with horizontal and
sagittal planes
• Enters the lateral wall of nasopharynx 1.25 cm behind
posterior end of inferior turbinate

Parts
• Lateral 1/3 - bony
• Medial 2/3 - fibro-
cartilaginous
• Junction between 2
parts -- isthmus,
narrowest part of
Eustachian tube

Anatomy of medial 2/3rd
• Cartilage plate
– Lies postero-medially
– Consists of medial and
lateral laminae separated
by elastin hinge
• Fibrous tissue and
Ostmann’s fat pad lie infero-
laterally

Muscles
1. Tensor veli palatini or dilator tubae
2. Levator veli palatini
3. Salpingopharyngeus
4. Tensor tympani
Nerve supply
1. Sphenopalatine ganglion
2. Mandibular nerve
3. Tympanic plexus

• Lining epithelium
− Respiratory epithelium
• Arterial supply
– Ascending pharyngeal & middle meningeal
arteries
• Venous drainage
− Pharyngeal & pterygoid venous plexus
• Lymphatic drainage
− Retropharyngeal node

Endoscopic Anatomy
• Medial end forms tubal
elevation / torus tubaris
• Lymphoid collection over
torus is called Gerlach’s tubal
tonsil
• Postero-superior to torus is
fossa of Rosenmüller

Adult vs. Child (< 7 yr)

Adult vs. Children (< 7 yrs)
ADULT INFANT
Length 36 mm 18 mm
Angle with horizontal 45 0 10 0
Lumen Narrower Wider
Angulation at isthmus Present Absent
Cartilage Rigid Flaccid
Elastic recoil Effective Ineffective
Ostmann’s fat More Less

Physiology
• Bony part is always open
• Fibro-cartilaginous part closed at rest and opens on
swallowing , yawning, sneezing, atmospheric pressure changes
• Active opening by contraction of tensor veli palatini
• Passive opening by contraction of levator veli palatini
(releases the tension on tubal cartilage)
• Closure : Elastic recoil of elastin hinge and deforming force of
Ostmann’s fat pad

E.T. opening

Functions
1. Ventilation & maintenance of atmospheric pressure in
middle ear for normal hearing
2. Drainage of middle ear secretions into nasopharynx by
mucociliary clearance, pumping action & presence of intra-
luminal surface tension
3. Protection of middle ear from
• Ascending nasopharyngeal secretions (due to narrow
isthmus & angulation at isthmus)
• Pressure fluctuations
• Loud sound coming through pharynx

Functions

Conditions of Dysfunction

Tests for E.T. function

1. Valsalva Maneuver
• Forced expiration with
mouth & nose closed
• Otoscopy shows lateral
bulging of Tympanic
membrane

2. Frenzel Maneuver
• Hands free Valsalva
• Compression of nasopharyngeal
air by muscles of tongue
• Otoscopy shows lateral bulging
of tympanic membrane

3. Toynbee Maneuver
• More physiological
• Swallowing with mouth &
nose closed
• Otoscopy shows retraction
of tympanic membrane

• Air pressure is alternately
increased & decreased within
external auditory canal
• Mobility of tympanic membrane
is observed with Siegel’s
pneumatic speculum/
pneumatic bulb of the otoscope
• Normal mobility indicates good
patency of Eustachian tube
4. Pneumatic otoscopy & Siegelization

Results of Siegelization
Position Mobility
Normal TM Neutral Moves briskly with
both positive and
negative pressures
ETD Retracted Moves with negative
pressure
Early OME Retracted Moves with negative
pressure
Air bubbles and fluid
seen
Late OME Retracted/ Bulge Poor with both positive
and negative pressures
ASOM Full to bulge Poor with both positive
and negative pressures

5. Politzerization
• Rubber tube attached to a Politzer bag put into one
nostril and both nostrils are pinched
• Patient asked to swallow or repeat “k”
• Politzer bag is squeezed simultaneously
• Otoscopy shows lateral bulging of ear drum in patent
Eustachian tube

6. E.T. catheterization
• E.T. catheter passed along nasal floor till it touches
posterior wall of nasopharynx
• Catheter rotated 90° medially & pulled forward till it
impinges on posterior nasal septum
• Catheter rotated 180° laterally, & its tip inserted into
opening of E.T.
• Politzer bag attached to outer end of catheter

• Air pushed into E.T. catheter by squeezing Politzer
bag
• Examiner hears by Toynbee auscultation tube put in
pt's ear
• Blowing sound  normal E.T. patency
• Bubbling sound  middle ear fluid
• Whistling sound  partial E.T. obstruction
• No sound  complete obstruction of E.T.

Eustachian tube catheter

7. Tympanometry
• Type C = E.T. dysfunction
• Type B = fluid in middle ear

8. Sono-tubometry
• Sound made in pt’s nasal cavity & detected with
stethoscope in patient’s external auditory canal
• Loud sound = patent Eustachian tube
9. Eustachian tube Salpingogram
• Dye instilled through E.T. catheter & X-ray taken
10. C.T. scan & M.R.I. of skull
11. Trans-nasal E.T. video-endoscopy

12. Test for E.T. patency in T.M. perforation
• Saccharine crystal / antibiotic ear drop /
methylene blue placed in middle ear via ear drum
perforation
• Sweet taste / bitter taste / blue staining of
secretions indicates patent Eustachian tube