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Anatomy of Middle Ear - NEET PG ENT

Feb 13, 2023

Anatomy of Middle Ear

The anatomy of middle ear is a crucial topic for the NEET PG exam because the middle ear is a complex and vital part of the ear and auditory system. The anatomy of the middle ear is closely related to the physiology of hearing and balance. 

A deep understanding of the anatomy of the middle ear helps in understanding and diagnosing conditions such as otitis media, tympanic membrane perforation, otosclerosis, and other ear diseases.

It is a critical aspect of otolaryngology, and a comprehensive understanding of its structure and function is essential for success in the NEET PG exam and in the practice of medicine.

Read this blog to get a quick overview of this important ENT topic.



Middle ear cleft= Middle ear + Mastoid + ET

Middle ear volume is 1 ml. Mastoid volume is 5 ml. ET is closed at rest, so we don’t consider the volume. Middle ear cleft volume is 6 ml. Middle ear is communicating with the mastoid by an opening K/as Aditus. Mastoid antrum is the largest air cell in mastoid. Antrum is of adult size at birth

Middle ear mastoid is covered by a bony plate; that separates the middle ear mastoid from middle cranial fossa. The plate is K/as Tegmen or Dural plate. Tegmen /Dural plate is divided into 2 parts: The part that covers middle ear is K/as Tegmen tympani and the parts that covers mastoid is K/as Tegmen antri (just above antrum)

TM forms the lateral wall of the middle ear.

lateral wall of the middle ear
  • TM divides middle ear into 3 parts:
    • Part above TM is Epitympanum/ Attic 
    • Part In Front TM is Mesotympanum
    • Part below TM is Hypotympanum 
  • Lateral bony wall of Epitympanum is K/as Scutum.
  • Erosion of scutum is the important sign seen in CT scan of Primary Acquired Cholesteatoma. Roof of mastoid/middle ear is tegmen 
  • Tegmen has a bulge which can be seen from the cranial side. It is K/as Arcuate Eminence, it is due to push by superior semicircular canal. It is the important surgical landmark for facial nerve surgery in the middle cranial fossa approach.



Also Read: Fetal Veins, Portal vein formation, Derivatives of the embryonic veins - NEET PG Anatomy

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Open Middle ear

  • Anterior wall contains 2 openings
    • Upper small opening for canal of Tensor tympani.
    • Lower big opening for Eustachian tube/auditory tube (ET connects middle ear to nasopharynx) 
  • Medial wall contains 2 windows 
    • Oval window/ Fenestra Vestibuli: It is covered by a footplate of stapes. Round window/Fenestra cochleae: It is covered by secondary TM.
    • There is a hook-like structure K/as Processus Cochleariformis, which forms a hook for tensor tympani muscle. [Tensor tympani starts in the anterior wall from the canal and goes to medial where it turns at Processus Cochleariformis and comes out laterally and attaches to handle of malleus]
    • Horizontal segment/tympanic segment of facial nerve. (Facial nerve is in the bony canal K/as fallopian canal, it is the largest bony canal for the CN, Length of fallopian canal is 27 mm) Postero superior to facial nerve there is a dome of lateral semicircular canal on medial wall of ME. This is the M/C site for Labyrinthine fistula 
    • There is a bulge in the medial wall K/as Promontory. It is due to the first turn/basal turn of cochlea. 
  • Posterior wall 
    • Opening K/as Aditus which connects ME to mastoid. Vertical segment/ mastoid segment of facial nerve
    • Pyramid: Stapedius muscle arises from here and attaches to the neck of stapes. Area medial to facial nerves is Sinus tympani (ME site for Recurrence / Residual cholesteatoma), it is a blind sac. Area lateral to facial nerve and above cauda facial angle is K/as Facial recess (this the M/C site for Posterior Tympanotomy)
    • Inferior wall/Floor      
  • Floor/inferior wall
Floor/inferior wall
  • Jugular bulb and internal carotid artery are present below the floor in between them there is a bony crest K/as Carotico Jugular Crest.
  • Phelp sign: Inability to distinguish between Jugular bulb and Carotid artery due to erosion of carotico jugular crest seen in glomus tumor. 

Also, read more medical notes blogs on different high-yield topics for strengthening NEET PG preparations. Download the PrepLadder app and get access to comprehensive study content curated by India’s best medical faculty.

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