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94 Cards in this Set

  • Front
  • Back
What are the 2 origin tissues of the eye?
1. Surface ectoderm
2. Neurocectoderm
Neural Ectoderm forms:
Optic sulcus
Optic Sulcus forms 2 things:
1. Optic vesicle -> Optic Cup -> Retina

2. Optic Stalk -> Optic nerve
Surface Ectoderm produces 2 thigns:
1. Lens placode

2. Corneal placode
Lens placode becomes:
Lens vesicle -> lens
Corneal placode becomes:
What is induced to form the optic sulcus?
What is induced to form the lens placode?
Optic vesicle
What is induced to form the corneal placode?
Lens vesicle
3 Eye formation defects:
1. Anophthalmia
2. Cyclopia
3. Synophthalmia
What is Anophthalmia?
Very small or absent eye
What causes
Primary anophthalmia?
2ndary anophthalmia?
1 = Genetics - eye involved only

2 = Forebrain defects
What is Cyclopia?
What is Synophthalmia?
Cyclopia = 1 eye, 1 orbit

Synophthalmia = 2 eyes, 1 orbit
What is the difference between neural and non-neural portions of the retina?
Neural = light sensing

Nonneural = light-accommodating
What is the only clinically visible part of the brain?
What is the outer retinal layer's optic cup composed of?
Pigmented epithelium
What is the inner layer composed of?
3 layers:
What happens to the inner layer?
Proliferates into 9 layers then develops after birth up to 2 yrs
What is the abnormality in Congenital Retinal Detachment?
The outer and inner layers do not fuse.
What happens as the NON-neural portion of the retina develops?
-Muscles develop
-Iris pigment develops
-Ciliary processes develop
What causes muscle devo in the non-neural portion?
Neural crest cells infiltrate and develop into Ciliary, dilator, and sphinctor muscles.
What causes iris pigmentation?
Pigment from the outer layer of the optic cup.
What contributes the ciliary processes?
Both layers of the optic cup
What are the 5 steps in lens formation?
1. Lens placode
2. Lens pit
3. Lens vesicle
4. Lens
5. Lens split: ant/post
What is the anterior lens?
What is the posterior lens?
Ant = Epithelium

Post = Lens fibers
What results from interference with lens devo?
Congenital cataracts
What does lens devo induce?
Cornea formation
From what 2 tissues does the cornea develop?
-Lens vesicle
-Neural crest
What does the lens vesicle form?
Corneal placode -> corneal epithelium
What does the Neural crest form? (2 things)
-Posterior endothelium
What are the 2 coverings of the eyeball? Main difference?
What is their origin?
1. Choroid layer - vascular
2. Sclera - avascular

-Both originate from Neural Crest
With what structures is the vascular choroid layer related?
Ciliary processes - anteriorly

Pia/arachnoid - posteriorly
With what structures is the avascular sclera related?
Cornea - anteriorly

Dura mater - posteriorly
Eyelids derived from what tissue?
Ectoderm - filled with mesenchyme
What facial processes form the eyelids?
Frontal prominence - upper

Max P = lower
What happens as the eyelids develop?
They grow over the eyeball, fuse, then reopen before birth.
Lacrimal apparatus derived from what tissue:
Extraocular muscles derived from:
Paraxial mesoderm from somitomeres
What do the extraocular muscles attach to (eye layer)
Vitreous body is derived from:
What is the difference between 1' Vitreous body and 2'?
1' = supplied by hyaloid artery

2' = avascular
What is the purpose of aqueous chambers?
Fluid removal
What is congenital glaucoma?
Abnormal devo of the fluid draining space in the eye
2 vascular structures supply the eye:
(where/what happens to them)
1. Hyaloid - initial; lens, vitreous, retina; degenerates before birth.
2. Choroid - around outer layer optic cup
What is the name for when the hyaloid artery doesn't degenerate and leaves vessels in front of the lens?
Persistent pupillary membrane
3 defects of eye development:
1. Coloboma
2. Congenital Ptosis
3. Microphthalmia
What is coloboma?
Failure of choroid fissure to close
What is congenital ptosis?
Failure to form levator palpebrae muscle
What is microphthalmia?
small eyeball
What will result if insult
-Before week 4?
-After week 8?
Before wk4 = functional problems

After wk8 = normal function
What 4 parts of the temporal bone support the ear? What arches are they derived from?
1. Petromastoid - Otic capsule
2. Styloid process - Arch 2
3. Squamous - Arch 1
4. Tympanic - Arch 1
What temporal bone parts are associated with
-External canal
-Internal meatus
EC = Petromastoid + Styloid Proc

IM = Squamous + Tympanic
What does the external ear develop from?
1st Pharyngeal cleft
What are the 2 components of the external ear?
1. Auricle
2. External auditory meatus
What structures begin devo of the auricle? What pharyngeal arches contribute them?
6 Hillocks:
3 - from Arch 1
3 - from Arch 2
How does the auricle migrate?
Starting in neck, then superodorsally.
What are the 3 primary components of the external auditory meatus? What is each derived from?
1. Cartilage (1st cleft)
2. Osseous (meatal plug)
3. Meatal plate (meatal plug end)
What is the meatal plug?
An inward extension of ???; continues to form until ~10 yrs
What is the Meatal Plate?
The external surface of the tympanic membrane.
What is the precursor tissue of the middle ear?
1st Pharyngeal Pouch
3 components of the middle ear:
1. Tympanic cavity (1st pouch)
2. Ossicles (arches 1/2)
3. Tympanic membrane - 3 layers
What arches are the ossicles derived from? (3 bones)
Malleus/Incus - Arch I

Stapes - Arch II
What are the 3 layers of the tympanic membrane and their precursors?
1. Ectoderm - 1st cleft
2. Endoderm - 1st pouch
3. Arch mesenchyme - Neural crest
What IS the tympanic membrane?
A closing plate.
From what 2 structures does the inner ear develop?
-Otic Vesicle
-Periotic mesenchyme
From what does the otic vesicle develop and how?
From the Rhombencephalon:
Otic placode -> pit -> vesicle
What develops out of the otic vesicle? (2 things)
-CN 8
-Membranous labyrinth
What other tissue contributes to inner ear devo? (other than rhombenceph)
Periotic mesenchyme -> otic capsule -> Petrous part of temporal bone
The otic vesicle develops into what 3 things:
-Endolymphatic appendage
-Utricle (dorsal portion)
-Saccule (ventral portion)
What is the structure of the Utricle like?
-3 extensions (Semicirc canals)
-Crista ampullaris
What is crista ampullaris?
The structure that detects fluid movement in the semicircular canals (balance)
What does the Saccule become?
What special structure is in it?
Cochlea via elongating
-Organ of Corti
What is the Organ of Corti function?
Detecting vibration in the cochlea - hearing.
6 defects of the external ear:
1. Anotia/microtia
2. Auricular tags
3. Auricular sinus
4. Otocephaly/Synotia
5. First arch syndrome
6. Meatal atresia
Absence of or small auricles
Auricular tags:
Accessory auricular hillocks
Auricular sinus
ABnormal 1st cleft development
Low-set ears (first arch)
First arch syndromes
Abnormal mandible development - causes low set ears
Meatal atresia
Failure of the meatal plug to canalize
2 defects of middle ear devo:
1. Congenital fixation of stapes
2. Cholesteatoma
Symptoms of congen. fixation of stapes:
-Hearing loss
-Autosomal dominant
Cholesteatoma is:
extra endodermal tissue in the middle ear
Defect of innear ear devo:
Vestibular cochlear dysplasia - underdeveloped SC canals and cochlea.
How much deafness is caused by congenital hearing loss?
2 main types of congen. hearing loss (CHL):
1. Conduction

2. Sensorineural
What is the defect in Conduction type CHL?
Problem conducting vibration through external and middle ear
What is the defect in Sensorineural type CHL?
Problem interpreting vibration by the inner ear and CN 8
4 causes of CHL:
1. Genetic (autosomal recessive)
2. Infection
3. Environment
4. Idiopathic
What type of inheritence pattern usually causes CHL?
Autosomal recessive
What infection can cause CHL?
What environmental factors contribute to CHL?
Drugs - Thalidomide/Acutane
How is an infant's ear unique from adult?
Short, straight, shallow, horizontal
What can result from the infant ear's structure?
Ear infections - otitis media