Transcript Anatomy & Physiology of Eustachian Tube

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 fibrocartilaginous.

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
 Loud
fluctuations
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
4. Pneumatic otoscopy &
Siegelization

Air pressure is alternately increased &
decreased within external auditory canal

Mobility of tympanic membrane is observed

Normal mobility indicates good patency of
Eustachian tube
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
8. William’s pressure
equalization test

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
William’s Test
Residual 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