Phylogeny and Embryology Flashcards
What is phylogeny?
The history of how a species evolves, particularly in relation to genetics
What is the fish’s “equilibrium organ” called?
Lateral line
Why do different species hear different ranges of frequencies?
Species evolve to hear the frequencies of their communication range
When are the middle and inner ear formed?
By Week 10
During what weeks do hair cells differentiate and grow?
Weeks 11-21
By what week does the outer ear reach adult form?
Week 20
By what week can the brain actually hear and encode sounds?
Week 25
Describe the Week 3 process that creates the otic vesicle.
- The ectoderm thickens. 2. A divit called the “otic placode” starts pushing into the structure. 3. Forms a hold called the “otocyst,” or “otic vesicle. This vesicle will later lengthen and spiral into the cochlea.
What is the membranous labrynth?
The entire inner ear, including the cochlea and vestibular organs
Which germ layer do the middle ear and eustacian tube develop from?
Endoderm
What week do the ossicles form?
Week 5
What are hillocks?
The bumps of the pharyngeal arches that form the pinna
What week do the ossicles begin to ossify?
Week 15
True or false: If there is a deformed outer ear, it is likely that there will be an issue with the middle ear, as well.
True. The outer and middle ear develop at the same time and in close proximity.
What frequencies are carried the best through fluids?
20-200 Hz
