CSD 251 unit 1

Ontogeny

the series of steps that ultimately leads to a mature state

Embryogenesis

the formation and development of an embryo

5 stages of embryogenesis

1. fertilization

2. cleavage

3. blastulation

4. implantation

5. embryonic disc

What happens by 5 weeks of pregnancy

two small spots appear on either side of the embryo’s head which eventually become the inner ear

What happens by 8 weeks of pregnancy?

middle ear begins to form

What happens by 12 weeks of pregnancy?

hair cells develop

What happens by 22 weeks of pregnancy?

the fetus hears sounds from inside the mothers womb

What happens by 23 weeks of pregnancy?

the fetus can hear sounds from the outside world

What happens by 26 weeks of pregnancy?

the fetus may begin to respond to the sounds it hears

What happens by 32-35 weeks of pregnancy?

post conception, the middle ear cavity, outer ear canal, and outside part of the ear are fully formed

Deafness caused during the fetal development is called?

congenital

What does congenital mean?

present at birth

What are the two basic categories of hearing loss?

1. non-genetic

2. genetic

Ototoxicity

from mothers placenta

Anoxia

happens as baby passes through the birth canal

Diseases

from the mothers placenta or birth canal

What are teratogens?

environmental agents that cause a birth defect

What is a syndrome?

a group of symptoms which consistently appear together

How many pairs of chromosomes do humans have?

23

What are the 3 basic types of simple genetic transmission?

1. autosomal dominant transmission

2. autosomal recessive transmission

3. X-linked transmission

What is a neural tube and why it is important for the development of ear structures?

• the fundamental embryonic structure that develops into the central nervous system, including the brain and spinal cord

• It is crucial for the development of ear structures because neural crest cells, migrate to form key components of the outer, middle, and inner ear. 

What does the pinna do?

collects sound and funnels it into the external auditory canal

Name the numbered parts of the ear

1. helix

2. darwin’s auricle

3. helix

4. anti-tragus

5. lobule of ear

6. tragus

7. concha (cymba/cavum)

The outer lateral 1/3 portion of the ear is what?

cartilaginous

The inner medial 2/3 portion of the ear is what?

bony

Cerumen=?

ear wax

osseous=?

bony

The outer ear protects the tympanic membrane from what?

-foreign bodies

-changes in humidity

-changes in temperature