Table 2-1 Flashcards
Fetal Week 3
INNER EAR
- Auditory Placode
- Auditory pit
MIDDLE EAR
-Tubotympanic recess beings to develop
Fetal Week 4
INNER EAR
- Auditory vesicle (otocyst)
- Vestibular-cochlear division
EXTERNAL EAR
-Tissue thickenings begin to form
Fetal Week 5
EXTERNAL EAR
-Primary auditory meatus begins
Fetal Week 6
INNER EAR
- Utricle and saccule present
- SCCs begin
EXTERNAL EAR
- 6 hillocks evident
- Cartilage begins to form
Fetal Week 7
INNER EAR
- 1 cochlear coil present
- Sensory cells in utricle & saccule
EXTERNAL EAR
-Auricles move dorso-laterally
Fetal Week 8
INNER EAR
- Ductus reuniens present
- Sensory cells in SCCs
MIDDLE EAR
- Incus & malleus present in cartilage
- Lower 1/2 tympanic cavity formed
EXTERNAL EAR
-Outer cartilaginous 1/3 of external canal formed
Fetal Week 9
MIDDLE EAR
-3 tissue layers at TM are present
Fetal Week 11
INNER EAR
- 2.5 cochlear coils present
- CN VIII attaches to cochlear duct
Fetal Week 12
INNER EAR
- Sensory cells in cochlea
- Membranous labyrinth complete
- Otic capsule begins to ossify
Fetal Week 15
MIDDLE EAR
-Cartilaginous stapes formed
Fetal Week 16
MIDDLE EAR
-Ossification of malleus & incus begins
Fetal Week 18
MIDDLE EAR
-Stapes begins to ossify
Fetal Week 20
INNER EAR
- Maturation of inner ear
- Inner ear adult size
EXTERNAL EAR
-Auricle is adult shape but continues to grow until 9;0
Fetal Week 21
MIDDLE EAR
-Meatal plug disintegrates, exposing tympanic membrane
Fetal Week 30
MIDDLE EAR
-Pneumatization of tympanum
