Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
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:
|
Cornea
|
|
What is induced to form the optic sulcus?
|
Diencephelon
|
|
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?
|
Retina
|
|
What is the outer retinal layer's optic cup composed of?
|
Pigmented epithelium
|
|
What is the inner layer composed of?
|
3 layers:
-Ventricular -Intermediate -Marginal |
|
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
-Stroma |
|
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:
|
Ectoderm
|
|
Extraocular muscles derived from:
|
Paraxial mesoderm from somitomeres
|
|
What do the extraocular muscles attach to (eye layer)
|
Sclera
|
|
Vitreous body is derived from:
|
mesoderm
|
|
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 |
|
Anotia/microtia:
|
Absence of or small auricles
|
|
Auricular tags:
|
Accessory auricular hillocks
|
|
Auricular sinus
|
ABnormal 1st cleft development
|
|
Otocephaly/Synotia
|
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?
|
60%
|
|
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?
|
Rubella
|
|
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
|