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