1. Middle ear

2. Middle ear structures Middle ear cavity/tympanum Tympanic membrane
Ossicles/Middle ear bones

3. Middle ear cavity Approximately 2 cm3 in volume Comprised of
Tympanic cavity between outer and inner ear
Epitympanic recess above the TM
Mastoid recess contained in the mastoid region of the temporal bone

4. Tympanic cavity Similar to a box with six surfaces
Lateral wall or membraneous wall: Formed by TM
Medial wall or labyrinthine wall: Promontory (outer wall of inner ear)
Contains oval and round windows
Anterior wall or carotid wall
Posterior wall or mastoid wall
Inferior wall or jugular wall
Superior wall or tegmental wall

5. Tympanic membrane Located in a bony groove
Held in place by fibers and cartilage
Cone shaped, translucent
55 to 90 mm2 in area

6. Tympanic membrane, cont’d.
Composed of two sets of fibers:
Radiates outward from center
Rings of fibers
Two regions in tympanic membrane:
Superior region: Pars flaccida
Inferior region: Pars tensa

7. Tympanic membrane, cont’d.
Umbo: Region of maximum concavity
Tympanic membrane attached to ossicles.

8. Ossicles Malleus: Hammer Incus: Anvil
Stapes: Stirrup
Head of malleus and body of incus located in the epitympanic recess

10. Malleus
Head
Anterior and posterior processes
Handle or Manubrium

11. Incus Body Short crus/process Long crus/process
(Plural of crus: Crura)

12. Stapes Head or capitulum Two bony crura
Flat oval bone called footplate