Difficult Head & Neck Anatomy: The Middle Ear & Ossicles · 2018-09-18 · Difficult Head & Neck...

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Difficult Head & Neck Anatomy: The Middle Ear & Ossicles Benjamin Huang, MD,MPH University of North Carolina at Chapel Hill Disclosures • None Objectives By the end of this lecture, you should be able to: Name the compartments of the middle ear and their contents Describe the anatomy of the ossicles Identify normal muscles and ligaments in the middle ear Describe the tympanic course of the facial nerve Identify key anatomic windows and spaces associated with the middle ear Lecture Organization Middle ear overview • Ossicles Muscles and tendons Facial nerve Windows, spaces and recesses The Tympanic Cavity Epitympanum Mesotympanum Hypotympanum The Tympanic Cavity Mastoid Antrum Epitympanum Aditus ad Antrum

Transcript of Difficult Head & Neck Anatomy: The Middle Ear & Ossicles · 2018-09-18 · Difficult Head & Neck...

Page 1: Difficult Head & Neck Anatomy: The Middle Ear & Ossicles · 2018-09-18 · Difficult Head & Neck Anatomy: The Middle Ear & Ossicles Benjamin Huang, MD,MPH University of North Carolina

Difficult Head & Neck Anatomy:

The Middle Ear & Ossicles

Benjamin Huang, MD,MPH University of North Carolina at

Chapel Hill

Disclosures

•  None

Objectives

By the end of this lecture, you should be able to: •  Name the compartments of the middle ear and

their contents •  Describe the anatomy of the ossicles •  Identify normal muscles and ligaments in the

middle ear •  Describe the tympanic course of the facial nerve •  Identify key anatomic windows and spaces

associated with the middle ear

Lecture Organization

•  Middle ear overview •  Ossicles •  Muscles and tendons •  Facial nerve •  Windows, spaces and recesses

The Tympanic Cavity

Epitympanum

Mesotympanum

Hypotympanum

The Tympanic Cavity

Mastoid Antrum

Epitympanum

Aditus ad Antrum

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The Tympanic Cavity

Mesotympanum

Protympanum

NPC Causing Mastoid Effusion

The Ossicles

•  Malleus → Incus → Stapes •  Transmit and amplify

sound vibrations from tympanic membrane to oval window

•  Mnemonic: “M I S O”

Top image: By Oreilleinterne.jpg: Marc GiaconeSVG version/translation: Angelito7 - Oreilleinterne.jpg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=59840795

Malleus

Malleus Head Neck

Lat. Proc. Manubrium

Incus

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Incus

Short Proc.

Long Proc.

Lenticular Proc.

Manubrium

Malleus Incus

Sag. “Molar Tooth” View

Suspensory Ligaments of the Ossicles

Suspensory Ligaments •  Anterior malleal •  Lateral malleal •  Superior malleal •  Posterior incudal

Stapes Muscles in the Middle Ear

Two middle ear muscles: •  Tensor tympani

–  Runs in canal along roof of bony Eustacian tube –  Turns at cochleoriform process before inserting on

malleus neck –  Innervation: CN V3

•  Stapedius –  Smallest muscle in human body –  Located adjacent to FN in pyramidal eminence –  Inserts on stapes neck –  Innervation: CN VII

Tensor Tympani

Incus lenticular process

Stapes neck

Stapedius tendon

Stapedius Muscle

Stapedius belly

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Facial Nerve Facial Nerve

Windows and Recesses

Windows •  Oval window •  Round window Spaces & Recesses •  Prussak’s space •  Facial recess •  Sinus tympani •  Supratubal (anterior epitympanic) recess

Oval Window Fenestral otospongiosis

Page 5: Difficult Head & Neck Anatomy: The Middle Ear & Ossicles · 2018-09-18 · Difficult Head & Neck Anatomy: The Middle Ear & Ossicles Benjamin Huang, MD,MPH University of North Carolina

Round Window Prussak’s Space

Left image courtesy of Dr Piotr Gołofit, Radiopaedia.org, rID: 43407

Epitympanic Cholesteatoma Facial Recess & Sinus Tympani

Facial Recess

Pyramidal Eminence

Sinus Tympani

Anterior Epitympanic (Supratubal) Recess

Epitympanic Cog

Supratubal Recess

Epitympanum

Summary

•  Middle ear compartments •  Ossicular anatomy

–  “M I S O” •  Muscles & tendons

– Only 2: Tensor tympani & stapedius •  Facial nerve •  Windows, spaces & recesses

– Put these in your checklist

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CROSS SECTIONAL ANATOMY REVIEW

CN7 - Labyrinthine

Geniculate ganglion

Epitympanum Additus ad

antrum

Mastoid antrum

Koerner septum

Head of malleus

Additus ad antrum

Mastoid antrum

AXIAL CT ANATOMY

Head of malleus

Incus body and short process

Tensor tympani

CN7 – tympanic segment

Anterior malleal lig.

AXIAL CT ANATOMY

Oval window (stapes

footplate)

Neck of malleus

Stapes crura

Tensor tympani tendon

Incus long process

CN7 – descending (mastoid) segment

AXIAL CT ANATOMY

Cochleoriform process

Manubrium of malleus

Incudo-stapedial

joint

Round window

Pyramidal eminence (CN7 & Stapedius)

Facial recess

Sinus tympani

AXIAL CT ANATOMY

Pro- tympanum

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CORONAL CT ANATOMY

Head of malleus

CN7

Tensor tympani tendon

Prussak’s space

Tegmen tympani

Neck & lateral process of malleus

CN7 –tympanic segment

Tegmen tympani

Scutum

Incus body &

long process

Incus - Lenticular Process

Stapes entering oval window

CORONAL CT ANATOMY

CN7 – tympanic segment

Round window

Incus short

process

CORONAL CT ANATOMY

Stylomastoid foramen

CN7 – mastoid segment

Posterior SCC

Lateral SCC

Internal jugular

vein

Superior SCC

CORONAL CT ANATOMY