Anatomy & Physiology of

Eustachian Tube

Dr. Vishal Sharma

History & Embryology

Bartolomeus Eustachius first described it as

pharyngo-tympanic tube in 1562.

Antonio Valsalva named it Eustachian tube.

Develops from tubo-tympanic recess, derived

from endoderm of 1st pharyngeal pouch.

Bartolomeus Eustachius

Antonio Maria Valsalva

Embryology

Anatomy

Anatomy

36 mm long in adults.

Directed anteriorly, inferiorly & medially from

anterior wall of M.E., forming angle of 450 with

horizontal & sagittal planes.

Enters naso-pharynx 1.25 cm behind posterior

end of inferior turbinate.

Angulation

Pharyngeal opening

Parts Lateral 1/3 is bony

Medial 2/3 is fibro-

cartilaginous.

Junction b/w 2 parts

is isthmus, narrowest

part of Eustachian

Tube.

Anatomy of medial 2/3rd

Cartilage plate lies

postero-medially &

consists of medial +

lateral laminae separated

by elastin hinge. Fibrous

tissue + Ostmann’s fat

pad lie antero-laterally.

Anatomy

Muscle attachments:

1. tensor veli palatini or dilator tubae

2. levator veli palatini

3. salpingopharyngeus

4. tensor tympani

Nerve supply: 1. Sphenopalatine ganglion

2. Mandibular nv 3. Tympanic plexus

Anatomy

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 tubarius

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. Child (< 7 yr)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 is closed at rest.

Opens on:

1. swallowing 2. yawning

3. sneezing 4. forceful inflation

Physiology

Opens actively by contraction of tensor veli

palatini & passively by contraction of levator

veli palatini (it releases the tension on tubal

cartilage).

Closes by elastic recoil of elastin hinge +

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 muco-ciliary clearance,

pumping action of Eustachian tube &

presence of intra-luminal surface tension

Functions

3. Protection of middle ear from:

Ascending nasopharyngeal secretions due

to narrow isthmus & angulation between 2

parts of E.T. at isthmus

Pressure fluctuations

Loud sound coming through pharynx

Functions

Conditions of Dysfunction

Bluestone’s Flask Model

Adult vs. Pediatric

TM perforation & nose blowing

O.M.E. & Barotrauma

Grommet insertion in O.M.E.

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 for pilots

Compression of nasopharyngeal air by

muscles of tongue

Otoscopy shows lateral bulging of tympanic

membrane

2. Frenzel Maneuver

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

Normal mobility indicates good patency of

Eustachian tube

4. Pneumatic otoscopy & Siegelization

Siegelization

Pneumatic Otoscope

Normal Tympanic Membrane

Eustachian Tube dysfunction

Early otitis media with effusion

Late otitis media with effusion

Acute suppurative otitis media

Ear drum perforation

5. Politzerization

Politzer Bag

5. Politzerization

Rubber tube attached to a Politzer bag put into

one nostril & both nostrils 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

Eustachian tube catheter

6. E.T. catheterization E.T. catheter passed along nasal floor till it

touches posterior wall of naso-pharynx.

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

6. E.T. catheterization

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.

7. Tymapanometry

7. Tymapanometry

Type C = E.T. dysfunction

Type B = fluid in middle ear

200 mm H2O pressure is created in patient’s

external auditory canal

Patient asked to swallow 10 times

Residual pressure in patient’s external auditory

canal after 10th swallow is noted

Test repeated with -ve 200 mm H2O pressure

created in patient’s external auditory canal

8. William’s pressure equalization test

William’s TestResidual Pressure Result

Up to + 50 mm H2O normal E.T. function

+ 51 to + 100 mm H2O mild dysfunction

+ 101 to + 199 mm H2O moderate dysfunction

+ 200 mm H2O severe dysfunction

9. Sono-tubometry

Sound made in pt’s nasal cavity & detected with

stethoscope in patient’s external auditory canal

Loud sound = patent Eustachian tube

10. Eustachian tube Salpingogram

Dye instilled through E.T. catheter & X-ray taken

11. C.T. scan & M.R.I. of skull

12. Trans-nasal E.T. video-endoscopy

13. 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

Patulous Eustachian Tube

Clinical Features

Aural fullness, humming tinnitus, hearing their

own voice (autophony), hearing their own breath

sounds (tympanophonia).

Symptoms resolve in supine position, in forward

bending with head between knees, in U.R.T.I.

Aggravated by mastication.

Otoscopy: T.M. moves during breathing.

Associated conditions: radiation therapy,

hormonal therapy, nasal decongestants, 3rd

trimester pregnancy, stress, sudden weight

loss, multiple sclerosis.

Treatment: Reassurance, weight gain, oral

potassium iodide.

Surgical interventions

1. Electro-cauterization of E.T. orifice

2. Peri-tubal injection with Teflon paste

3. Transposition of tensor veli palatini muscle

medial to pterygoid hamulus

4. Plugging of E.T. orifice in Middle ear +

myringotomy & grommet insertion

Thank You