Development of the Ear and Eye Flashcards
What is a placode?
Thickened ectodermal patches on the developing head
What are the pharyngeal apparatus?
Series of external ridges and furrows with corresponding internal pouches
What is the function of the internal ear?
Converts sound into electrical impulses
Which nerve innervates the inner ear apparatus?
Vestibulocochlear
Which 2 structures make up the inner ear?
Cochlear and Semicircular canals
How does ear development start?
Otic placodes form
What happens to the otic placodes as they develop?
Invaginate into the developing head to form the otic vesicles
What does the ventral portion of the otic vesicle become?
Saccule and cochlear duct
What does the dorsal portion of the otic vesicle become?
Utricle, semicircular canals and endolymphatic duct
What 2 things make up the Organ of Corti?
Sensory hair cells
Tectorial membrane
What is the function of the middle ear?
Conduct sound from the external acoustic meatus to the inner ear
What area is the middle ear derived from?
1st pharyngeal pouch
1st and 2nd pharyngeal cartilage
Which pharyngeal cartilage develops into the malleus and incus?
1st pharyngeal cartilage
Meckel’s cartilage
Which pharyngeal cartilage develops into the stapes?
2nd pharyngeal cartilage
Reichert’s cartilage
What structure is created by the narrowing of the 1st pharyngeal pouch proximally?
Eustachian tube
What does the external ear develop from?
Dorsal portion of the 1st pharyngeal cleft
What are the 3 layers of the tympanic membrane?
Ectoderm, mesoderm and endoderm layers
Where do the external ears initially develop?
Neck
In what week does the eye start developing?
4th week
Describe the initial process of eye formation?
Outpocketings of the forebrain called the optic vesicles grow to make contact with the overlying ectoderm to form the optic placode.
Decreibe the appearance of the optic cup
Inner and outer layer separated by a lumen creating the intraretinal space
What does the inferior surface of the optic cup become and what is its function?
Choroid fissure- carries hyaloid artery
What is the outer layer of the optic cup also known as?
Pigmented layer
What do the cells in the inner layer of the optic cup differentiate into?
Cons
Rods
Optic nerve
Neurones
What does the hyaloid artery become?
Central artery of the retina
What does the rim of the optic cup differentiate into?
Iris
Ciliary body
What does the loose mesenchyme surrounding the eye develop into?
Choroid
Sclera
What do the extraocular muscles develop from in the eye?
Preotic myotomes
What is coloboma?
Failure of the choroid fissure to fuse
