Ear development Flashcards
بسم الله الرحمن الرحيم
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Inner ear:
Membranous labryinth develops from …….
early in the …..week , athickeninig of the surface ectoderm “…..” appears on each side of the caudal part of………….
The …..invaginates and form …………
in the …..w.eek the ……(……) splits off from the surface of ectoderm
The …… divides into a ventral component called…..and dorsal one called ………
Otic Vesicle
4th week
Otic placode
hindbrain
Otic placode - otic pits
4th week otic vesicle ( otocytes)
otic vesicle dividned into ventral saccule and dorsal utricle
Inner ear develops from ….
myeloencephalon of hindbrain
The cochlear duct develops in ….week
as ……..from the lower pole of …….
It penetrates the surrounding ,,,,,, and forms 2 1/2 spirals .
its connections with the saccule is then confined to narrow pathway called,,,,,
the surrounding mesecnchyme becomes cartilage two perilmphatic spaces
………..+……… around choclear duct
6th week
tubular outpocket from lower pole of Otic vesicle
Mesenchyme
ductus reunins
scala vestibuli +scala tympani
Cochlear duct separated from scala vestibuli by …….
and from scala tympani by…..?
The lateral wall of choclear duct attaced to the cartilage by …….
The median angle connected to ….which will be the future …. of choclea
The epithelial lining the cochlear duct form inner and outre hair cells covered by ….. ?
Vestibular membrane
Basilar membrane
Spiral ligament
Modiluous the future angle of choclea
Tectorial membrane
Semicircular canal appears during …..week
developed from …..
6th week
utricle 3 flattened outpockets
How smicircular canals formed
?
During 6th week from the flattened 3 outpockets of utricle
2 walls of central potrions of each one are apposed disappaering forming the canals
superior
Posterio
Lateral semiciruclar canals
The ends of semiciulara canals forms ….. forming,,,,,,,,,,, mention its importance
Ampulla
Critsa amupillaris
sensory cells for equilibrium maintanance
Menetion innervation of inner ear
Vestibulo-cochlear ganglion formed by?
During formation of otic vescile a small group of cells breaks awary from the ganglion
May due to neural crest cells migration
Vestibulochoclear ganglion supplies ?
Sensory cells of Organ of Corti
Saccule Utricle and its semiciruclar canals
Middle ear development
The lining epithelium from the Endodermal tubotympanic membeane = 1st pharyngeal arch
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Osciles from the cartilage of 1st pharyngeal arch ( malleus - incus ) + 2nd pahryngeal arch (stapes)
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Muscles : Tensor tympani 1st arch = Manidbular supply
Stapedius 2nd arch = Facial nerve supply
During fetal life the tympanic cavity expands ……. by …… of the surrounding tissue forming ……. .
After birth the bone of the developing mastoid process is also ,,,,,,,
Later most of the mastoid air sacs come in contact with ,,,, + ,,,,,,,,
Dorsally - Vacuolation - mastoid antrum
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Pnematiezed - antrum -Tympanic membrane
External auditory meatus develops from ,,,,, pharyngeal arch ?
in the …. month the epitlial cells at its bottom proliferate forming a solid metal plug that dissoslves at ….. month if it ipersists = congenital dafness
First
3rd - 7th
Ear drum
tympanic membrane formed of ?
Ectodermal epithleial lining
Mesenchymal intermediate layer
Endodermal from first pharyngeal arch
The Six mesenchymal hillocks surrounding first pharyngeal arch fuse to form ?
Auricle
What it the initial site of external ear ?
Lower neck but with progression in development it ascends to its normal postion to sides of head at level of eye
Congenital deafness write shortly about
Associated with Deaf-mutism
due to :
1-Malformation of membranous or bony labyrinths
2-Malformation of Osciles + eardrum
3-absence of tympanic caivty or External auditory meatus
It is belieced to be hereditary but now we know it is asscoicated with : ERcP THD
Erythroblastosis fetalis
Rubella
Poliomyelities
Toxoplasmosis
Hyperthyroidism
Diabetes
Variation of auricle clinical imp mention
May be associated with
1-Kideny malfomatin
2-chormosme determined syndromes
3-First arch syndrome
Describe first and second order neurons of auditory pathway
1ST:
Cetnral process of bipolar cells From spiral ganglion in inner ear to internal acoustic meatus to pons
2nd :
From pons branching into 2 divisions one to dorsal and the other to ventral Choclear nuclei
theri axons forms trapezoid body then relay in Superior olivary nusclei+ Trapezoid nucleus of the same or opposite side
Describe 3rd and 4th order neurons of auditory path
3rd :Axons of superior olivary nucleus + trapezoid nuscleus ascneds in the lateral leminscus then to Nucelus of lateral leminscus sone relay and some contiunes then to Inferior colliculs some relay and some contiunues then to MGB
4th :
MGB gives audiotry raidation passing in the sublentifrom nucleus of Internal capsule then to area 41 primary auditory one
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