Eustachian tube

Anatomy, physiology and functional assessment

embryology Develops from endoderm of first pharyngeal

pouch

the distal portion of the pouch expands and forms middle ear cavity

Proximal portion forms the Eustachian tube

cartilage and muscles develop from surrounding mesoderm

anatomy Channel connecting tympanic cavity and

nasopharynx 36mm in length ( 31- 38 mm) lumen of the Eustachian tube is roughly

triangular, measuring 2-3 mm vertically and 3-4 mm horizontally.

Lined by respiratory epithelium with goblet cells and mucous glands

Opens at about 1- 1.25 cm behind and a little below posterior end of inferior turbinate

anatomy

anatomy

Bony part : 12mm long widest at tympanic end gradually narrows towards isthmus (2mm) Thin plate of separating from tensor tympani

superiorly Plate of bone separating from internal carotid

medially

anatomy

Cartilaginous part 24mm long Cartilage forms posteromedial wall and a

small portion anterolaterally sits in a groove between petrous temporal

bone and greater wing of sphenoid nasopharyngeal opening surrounded by tubal

elevation above and behind Fossa of Rosen Muller lying behind this tubal

elevation

Anatomy

Muscles attached to ET Levaor palati – lower surface of petrous bone

and cartilage and fascia of upper carotid sheath

Tensor palati- bony wall of scaphoid and whole length of short cartilaginous flange

Salphingo pharyngeus – inferior part of cartilage near its pharyngeal end

Tensor tympani – cartilage of ET, surrounding bony canal and greater wing of sphenoid

anatomy

Endoscopic view of ET opening

anatomy

Ostmann fat pad contributing factor in closing the tube in the inferolateral aspect of the Eustachian

tube

physiology

functions Pressure regulation

Clearance of middle ear space

Protection of middle ear space from nasopharyngeal pathogens and foreign bodies

physiology

Eustachian tube dysfunction

Etiology upper respiratory infections Allergic rhinitis Chronic sinusitis Adenoid hypertrophy Tobacco smoke Reflux Cleft palate Radiation Nitrous oxide

ETD

Pathological events Mucosal edema

Reduced lateral wall motion

Obstructive lesion

ETD

Evaluation of ET

History Fullness of ears

Pain and discomfort

Hearing loss

Tinnitus

Dizziness

Evaluation of ET

Physical examination Retracted TM Middle ear effusion Pneumatic otoscopy Postnasal examination Endoscopic examination

Evaluaton of ET

Valsalva maneuver Tonybee test Politzer test Sonotubometry

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