[ Home ] [ Up ] [ Course Schedule ] [ Links ]

Ear

Embryological Origins

Table 15 - Embryonic Origins of Structures in Adult Ear

Region

Tissue of Origin

Embryonic Structure

Adult Structures

Internal ear

Surface of hindbrain (ectoderm)

Otic vesicle
utricular portion

Utricle,
Semicircular ducts

 

 

Otic vesicle
saccular portion

Saccule
Cochlear duct
Coclea
Spiral organ (of Corti)

 

Mesenchyme surrounding otic vesicle

Otic capsule

Bony Labyrinth

Middle ear

Branchial arch 1

 

Incus
Malleus
Tensor tympani muscle

 

Branchial arch 2

 

Stapes
Stapedius muscle

 

Branchial pouch 1 (endoderm)

Tubotympanic recess

Auditory tube
Tympanic cavity
Mastoid antrum

 

Branchial groove 1 (ectoderm)

 

Tympanic membrane

External ear

Branchial grooves 1, 2 (ectoderm)

Auricular hillocks

Auricle

 

 

 

External acoustic meatus

The meatal plug is a mass of epithelial cells that plugs the medial end of the external acoustic meatus until about week 28 of development.  It normally disappears before birth.

Clinical Correlations

Congenital deafness

Genetic factors are involved in about one-third of cases of congenital deafness.  Infectious agents that can cross the placental membrane can also disrupt development of the spiral organ (of Corti) so that infection with the rubella virus or with Treponema palladium (the microorganism that causes syphilis) can cause congenital deafness.  Congenital deafness also frequently accompanies trisomy 13 and 18, as well as branchial arch anomaly syndromes.

 

[ Home ] [ Up ] [ Course Schedule ] [ Links ]
Copyright © 1999 University of Michigan Medical School
Unauthorized use prohibited
Send comments to Dr. Tom Gest <gest@umich.edu>.
Last modified: Thursday, 06-Jan-2000 18:11:38 UTC