Hearing - Outer Ear Development: Difference between revisions
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{| class="prettytable" | |||
| Pharyngeal Arch | |||
| Hillock | |||
| Auricle Component | |||
|- | |||
| Arch 1 | |||
| 1 | |||
| tragus | |||
|- | |||
| | |||
| 2 | |||
| helix | |||
|- | |||
| | |||
| 3 | |||
| cymba concha | |||
|- | |||
| Arch 2 | |||
| 4 | |||
| concha | |||
|- | |||
| | |||
| 5 | |||
| antihelix | |||
|- | |||
| | |||
| 6 | |||
| antitragus | |||
|} | |||
* Outer- external auditory meatus | |||
* derived from first pharyngeal cleft | |||
* ectodermal diverticulum | |||
* week 5 - extends inwards to pharynx | |||
* until week 18 has ectodermal plug - plug forms stratified squamous epithelia of canal and outer eardrum | |||
{| class="prettytable" | |||
| Embryonic period | |||
| Ectodermal cells proliferate and fill the entire lumen forming a meatal plug | |||
|- | |||
| 10 weeks | |||
| Meatal plug extends in a disc-like fashion. In the horizontal plane the meatus is boot-shaped with a narrow neck and the sole of the meatal plug spreading widely to form the future tympanic membrane medially. Proximal portion of the neck starts to be resorbed. | |||
|- | |||
| 13 weeks | |||
| Disc-like plug innermost surface in contact with the primordial malleus, contributes to the formation of the tympanic membrane. | |||
|- | |||
| 16.5 week | |||
| Meatus is fully patent throughout its length, lumen is still narrow and curved. | |||
|- | |||
| 18 week | |||
| Meatus is already fully expanded to its complete form. | |||
|} | |||
(Nishimura, 1992} | |||
Outer Ear Genes | |||
* controlled by genes that regulate arch 1 and 2 development | |||
* related to hindbrain segmentation (rhombomere 4) | |||
* Mouse - Hox a1/Hoxb1, goosecoid, Endothelin1, dHAND | |||
{{Template:Glossary}} | {{Template:Glossary}} |
Revision as of 12:19, 4 June 2010
Introduction
The external ear is derived from 6 surface hillocks (auricular hillocks), three on each of pharyngeal arch 1 and 2.
The external auditory meatus is derived from the 1st pharyngeal cleft.
Pharyngeal Arch | Hillock | Auricle Component |
Arch 1 | 1 | tragus |
2 | helix | |
3 | cymba concha | |
Arch 2 | 4 | concha |
5 | antihelix | |
6 | antitragus |
- Outer- external auditory meatus
- derived from first pharyngeal cleft
- ectodermal diverticulum
- week 5 - extends inwards to pharynx
- until week 18 has ectodermal plug - plug forms stratified squamous epithelia of canal and outer eardrum
Embryonic period | Ectodermal cells proliferate and fill the entire lumen forming a meatal plug |
10 weeks | Meatal plug extends in a disc-like fashion. In the horizontal plane the meatus is boot-shaped with a narrow neck and the sole of the meatal plug spreading widely to form the future tympanic membrane medially. Proximal portion of the neck starts to be resorbed. |
13 weeks | Disc-like plug innermost surface in contact with the primordial malleus, contributes to the formation of the tympanic membrane. |
16.5 week | Meatus is fully patent throughout its length, lumen is still narrow and curved. |
18 week | Meatus is already fully expanded to its complete form. |
(Nishimura, 1992}
Outer Ear Genes
- controlled by genes that regulate arch 1 and 2 development
- related to hindbrain segmentation (rhombomere 4)
- Mouse - Hox a1/Hoxb1, goosecoid, Endothelin1, dHAND
Glossary Links
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Cite this page: Hill, M.A. (2024, April 24) Embryology Hearing - Outer Ear Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Hearing_-_Outer_Ear_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G