Middle Ear Anatomy

Compartments of tympanic cavity

Epitympanum, mesotympanum, and hypotympanum

Six walls of middle ear

Anterior, roof, posterior, lateral, medial, and floor

lateral wall

Separates outer ear from middle ear.

Contains the TM and temporal bone

Medial wall

Separates middle ear from the membranous labyrinth of the inner ear.

Contains the promontory, oval window, round window, prominence of facial canal and lateral SSC

Muscle connects to the malleus

Tensor tympani muscle

Supplies blood to the brain, head, and neck

Internal carotid artery

Anterior wall

Internal carotid artery

Two openings: ET, tensor tympani muslce

ET direction 

Courses in an inferior, anterior, and medial direction. 

Runs from the anterior wall of the ME cavity to the nasopharynx

ET

Length of ET

35-38mm

ET osseous or cartilaginous?

Both. Outer 1/3 is bony, and stays open. Inner 2/3 is cartilaginous and is closed but can open by contraction and relaxation of the leavator and tensor veli palatini muscle

Posterior wall

aka mastoid wall

Pyramidal eminence houses the stapedius muscle 

aditus to mastoid antrum 

chorda tympani nerve

Superior wall

aka roof 

Formed by tegmen tympani

separates the the ME cavity and cranium 

Inferior wall

Formed by tympanic plate of temporal bone

separates the ME space and the jugular fossa

Ossicles

Incus, malleus, stapes

Connects malleus to stapes

Incus

Footplate of stapes is fastened to the oval window by..

annular ligament 

Part of the malleus that connects to the TM

manubrium

Attaches the manubrium to the malleus

tensor tympani muscle

Tensor tympani muslce innervated by what nerve

CN V, trigeminal nerve

Muscle attached to the head of the stapes

stapedius muscle

Stapedius muslce innervated by what nerve

CN VII, facial nerve

Green

Anterior crus

Footplate

Obduralor foramen

Posterior crus 

Head of stapes

Incudostapedial articulation

Blue

Head of the malleus

Neck of malleus

anterior process of malleus

Lateral process of malleus

Manubrium

Umbo

Yellow

Incudomalleal articulation

Body of incus

short process of incus

long process of incus

Lenticular process

Lenticular process connects to that

Stapes

1. Manubrium

2. Lateral process

3. Chroda tympani

4. Long process