Hearing - Outer Ear Development

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Hearing cartoon.jpg

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.

Hearing Links: Introduction | inner ear | middle ear | outer ear | balance | placode | hearing neural | Science Lecture | Lecture Movie | Medicine Lecture | Stage 22 | hearing abnormalities | hearing test | sensory | Student project

  Categories: Hearing | Outer Ear | Middle Ear | Inner Ear | Balance

Historic Hearing 
Historic Embryology: 1880 Platypus cochlea | 1902 Development of Hearing | 1906 Membranous Labyrinth | 1910 Auditory Nerve | 1913 Tectorial Membrane | 1918 Human Embryo Otic Capsule | 1918 Cochlea | 1918 Grays Anatomy | 1922 Human Auricle | 1922 Otic Primordia | 1931 Internal Ear Scalae | 1932 Otic Capsule 1 | 1933 Otic Capsule 2 | 1936 Otic Capsule 3 | 1933 Endolymphatic Sac | 1934 Otic Vesicle | 1934 Membranous Labyrinth | 1938 Stapes - 7 to 21 weeks | 1938 Stapes - Term to Adult | 1940 Stapes | 1942 Stapes - Embryo 6.7 to 50 mm | 1943 Stapes - Fetus 75 to 150 mm | 1946 Aquaductus cochleae and periotic (perilymphatic) duct | 1946 aquaeductus cochleae | 1948 Fissula ante fenestram | 1948 Stapes - Fetus 160 mm to term | 1959 Auditory Ossicles | 1963 Human Otocyst | Historic Disclaimer

Some Recent Findings

Pinna- Auricle

External ear stages 14-23 and adult (not to scale)
outer ear and external auditory meatus
  • develops from six aural hillocks
  • 3 on first arch
  • 3 on second arch
  • originally on neck, moves cranially during mandible development


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

References


Reviews

Articles

Search PubMed

May 2010 "Outer Ear Development" All (1478) Review (120) Free Full Text (215)

Search Pubmed: Outer Ear Development Pinna Development

External Links

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Cite this page: Hill, M.A. (2019, October 18) Embryology Hearing - Outer Ear Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Hearing_-_Outer_Ear_Development

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G