Development of Sense Organs / Establishment of Structures in the Head and Neck Region Flashcards
*ESTABLISHMENT OF THE EYE
Median area near the rostral margin of the future prosencephalon (neural tube) at the level of the diencephalon is called the ____
optic field
*ESTABLISHMENT OF THE EYE
- Interaction of this area to the underlying mesoderm of the head causes the single optic field to separate into two lateral eye forming regions
Failure to separate completely results to a condition called ____, single eye formed at the center of the head
cyclopia
*ESTABLISHMENT OF THE EYE
When the rostral end of the neural tube closed, the prosencephalon expands laterally, the optic field divide to form the ____ which retains its attachment to the
prosencephalon of thru the ____
optic vesicles
optic stalk
*ESTABLISHMENT OF THE EYE
Lens placode which subsequently invaginate to form the ____ then break away from the surface ectoderm
lens vesicles
*ESTABLISHMENT OF THE EYE
While the lens vesicle is being formed, optic vesicle invaginate to form a double layered ____
optic cup
*ESTABLISHMENT OF THE EYE
Outer layer forms the ____ while the inner layer becomes the ____ which is the light receptor area
pigmented retina
nervous retina
failure of the optic vesicle to form or interference with the normal growth of the optic cup; often result from deficiency of vitamin A in dogs, pigs, and cows; hereditary or acquired.
Anopthalmia/ micropthalmia-
medial/ lateral deviation of of the eyeball
Medial/ Lateral strabismus-
defect in the growth of the optic cup which is usually seen in the retina and choroid as a focal dysplasia
Collie eye-
loss in the clarity of the lens which maybe hereditary in dogs; appear occasionally in cattle, rarely in horses and cats
Cataract-
- The adult ear has three parts:
- External ear
- Middle ear
- Inner/ internal
composed of the pinna, external auditory meatus and outer layer of the tympanic membrane- sound waves collection
External ear
composed of the ear ossicles and inner layer of the tympanic membrane used for the conduction of sound waves
Middle ear
composed of the bony and membranous labyrinth which function for equilibrium
Inner/ internal ear
*ESTABLISHMENT OF THE EAR
- Of all the three parts of the ear, the ____ is the first to develop
- At the level of the myelencephalon ectoderm, a localized thickening on either side appear called the ____
internal ear
otic placode
*ESTABLISHMENT OF THE EAR
- Which then invaginate in the underlying mesoderm as otic pit then become _____
otic vesicle
- Develops after the formation and growth of the cochlear duct
- The inner and outer hair cells then differentiate into their appropriate positions and are followed by the organization of the supporting cells
- It is located in between the scala tynpani and the scala media
ORGAN OF CORTI
*Organ of Corti
- At ____, the utricle forms a flattened outpocketings
- The central portions appose and then disappear and forms the ____
- One end widens and become the ampulla
- During the formation of the otic vesicle, a small group of cells breaks away from its wall and forms the _____
- Also reinvested cells from the neural crest
6th wk
semicircular canals
statoacoustic ganglion
Components of Otic Vesicle (Otocyst)
- Ventral saccular portion (small constricted part)
- Dorsal utricular portion (small constricted part)
Components of which Otic Vesicle
- Saccule
- Cochlear duct (organ of Corti)
- Spiral ganglion of the vestibulo-cochlear nerve
Ventral saccular portion
Components of which Otic Vesicle
- Utricle
- Semicircular canal/ duct
- Endolymphatic duct
- Vestibular ganglion of the vestibulo cochlear nerve
Dorsal utricular portion
DEVELOPMENT OF THE MIDDLE EAR:
* Composed of:
- Eardrum/ tympanic membrane
- Tympanic cavity
- Malleus or hammer
- Incus or anvil
- Stapes (or stirrup)-
cone shaped membrane that separates the external ear from the middle ear
Eardrum/ tympanic membrane-
contains the 3 small bones
Tympanic cavity-
long handle attached to the eardrum
Malleus or hammer-
the bridge bone between the malleus
Incus or anvil-
the footplate; the smallest bone in the body
Stapes (or stirrup)-
*DEVELOPMENT OF THE MIDDLE EAR:
- At the ____, tubulotympanic sulcus develops as extension of the endodermal epithelium of the 1st pharyngeal pouch
- Distal part is the ____
- Proximal part is the ____
4th wk
primitive tympanic cavity
auditory tube/ eustachian tube
*The Ossicles PRIMORDIAL STRUCTURES:
____ derived from pharyngeal pouch 1 will give rise to the head of malleus and body of incus
Meckel’s cartilage
*The Ossicles PRIMORDIAL STRUCTURES:
____ derived from the pharyngeal arch 2 will give rise to the manubrium of malleus, long process of incus and supstructure of stapes
Reichert cartilage
*The Ossicles PRIMORDIAL STRUCTURES:
Development of the stapes is induced by a depression on the otic capsule, the ____
lamina stapedialis
THE EXTERNAL EAR
COMPOSED OF:
- External auditory meatus
- Tympanic membrane
- Auricle/ pinna-