The development of the middle and external ear explained in less than 15 minutes.
For the embryology of the inner ear, tap here: • Embryology of the Ear ...
If you are completely new to embryology and you want to understand it quickly, this should be the first video you watch:
- • Introduction to Embryo...
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SUMMARY OF THE VIDEO FOR YOUR NOTES
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The middle ear
- Tympanic cavity comes from the endoderm, from the first pharyngeal pouch.
- The pouch expands laterally until it touches the first pharyngeal cleft
- The distal part of the pouch is the tubotympanic recess, which widens becoming the primitive tympanic cavity. The proximal part remains narrow and becomes the auditory tube aka eustachian tube
- The malleus and incus come from the first pharyngeal arch
- The stapes comes from the second pharyngeal arch
- Tensor tympani is innervated by the mandibular branch of the trigeminal nerve
- Stapedius is innervated by the facial nerve
The external ear
- External auditory meatus comes from the first pharyngeal cleft
- The solid epithelial meatal plug will dissolve by the seventh month, otherwise the newborn will be deaf
- Th tympanic membrane (eardrum) is made from three layers: ectoderm epithelium, mesoderm middle layer which is connective tissue, and endoderm which is the inner mucous membrane (epithelium).
- The malleus' handle is in contact with the tympanic membrane.
- The auricle develop from 6 swellings called the auricular hillocks.
- Hillocks 1, 2, and 3 come from pharyngeal arch 1
- Hillocks 4, 5, and 6 come from the second arch
- The hillocks will eventually grow and fuse together in a complicated process that I have simplified by just saying "they all fuse together"
- 1 is the tragus, 2 is the helix, 3 is the cymba conca, 4 is the concha, 5 is the anti-helix, and 6 is the anti-tragus - lets keep it at that