Middle ear anatomy

Mastoid

-tegmen tympani -mastoid tantrums -mastoid air cells -whole nerve action potential can be recorded from here -aditus is what opens up to mastoid antrum

Tympanic membrane

-whole nerve action potential can be recorded right in front of TM -outer ear protects TM -cone shaped -3 layers

3 layers of tympanic membrane

1. Cutaneous (skin) 2. Fibrous (gives TM tension) 3. Mucous membrane

Anatomy of malleus

1. Head 2. Neck 3. Manubrium (umbo is tip of manubrium) -picture pointing to manubrium from outside the TM

Anatomy of stapes

1. Head (connects to incus) 2. neck 3. anterior crus 4. posterior crus 5. footplate

Anatomy of incus

1. Short process (stubby part) 2. Body (middle part) 3. Long process (long hooked part)

Muscles of middle ear

1. Tensor tympani (attaches to upper portion of manubrium of malleus) 2. Stapedius -both muscles don't show up in middle ear space, but in bony canal, the tendons however can be seen in the middle ear space

Incus

3 parts: body, short process, long process -long process of incus connects to head of stapes

Pars tensa

Contains all three layers- tense

Acoustic reflex

when the two muscles "reflex", they pull in opposite directions which stiffens ossicular chain and keeps it from vibrating as easily

Malleus

-connects to tympanic membrane in two areas -3 pars: head, neck, manubrium -umbo is tip of manubrium, attaches to TM -attaches to tensor tympani (which is a muscle in the middle ear)

Mastoiditis

-infection of the mastoid air cells, needed to be scooped out

Eustachian tube

-makes connection from nasopharynx -horizontal in children -collapsed in normal position

Stapes

-smallest bone -5 parts: footplate, posterior crus, anterior crus, neck, head -footplate rests on oval window -compression moves stapes

The ossicular chain

-TM connects to malleus -malleus connects to incus -Incus connects to stapes -stapes connects to oval window

Medial wall of middle ear cavity

-back wall is "medial" wall -oval window is opening to middle ear -round window is tucked back a bit more than oval window -facial nerve is orange tube=middle ear surgery can lead to facial paralysis -promontory= bulge of cochlea

Epitympanic recess

"epi" means above ... space above tympanic membrane -joint of first two bones is located here

Pars flaccid

"floppy", doesn't contain fibrous layer (tense part)

Tegman tympani

"paper thin", separates middle ear cavity from brain and epitympanic recess