CSD 251 FINAL

What is ontogeny

the series of steps that ultimately leads to a mature state

What is embryogenesis

the formation and development of an embryo

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 tubercle

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

The outer ear protects the tympanic membrane from what?

-foreign bodies

-changes in humidity/temperature

What do the structures within the EAC do?

-ceruminous and sebaceous glands form cerumen

- hairs and cerumen protect objects from getting into the TM

What is another name for pinna?

auricle

What does the tympanic membrane do?

separates the EAC from the tympanum or middle ear cavity

What are the two types of fibers in the middle layer of the tympanic membrane?

1. radial

2. spiral

What is the pars flaccida?

the upper portion of the TM where the rings of fibers are sparse

What is the pars tensa?

the lower portion of the TM where there are more fibers and the membrane is stronger

What is the umbo?

the very middle point of maximum concavity of TM; where the point of manubrium attaches to the medial (back) of TM

What does the eustachian tube do?

opens and closes to equalize pressure between middle ear and environment

The tympanic membrane holds what ossicles?

-malleus

-incus

-stapes

What does the annular ligament do?

supports the footplate of stapes in oval window

What are the axial ligaments?

posterior ligament (incus) and anterior ligament (malleus)

What is the tensor tympani connected to?

the upper part of the manubrium of the malleus by a tendon

What is the stapedial muscle?

the smallest muscle in the body that attaches to the head of the stapes

What are the 3 methods in which sound can be transmitted through the middle ear?

1. through bone conduction

2. thru air in the middle ear cavity

3. across the middle ear cavity by means of the ossicular chain

What are chilblains?

inflammation of small blood vessels on the skin caused by repeated exposure to cold

How does OME develop?

by bacteria/germs/pathogens migrating up the eustachian tube, which causes swelling+ obstruction

What are the 3 main reasons young children have more OME episodes?

1. the muscle responsible for opening and closing the ET (tensor veli palatini) is relatively inefficient among young infants+ children

2. the ET is angled 10 in young children, whereas it is angled 45 in adults

3. the ET is very short in infants, so fluid is able to reach the ME from nasopharyngeal area fairly easily

What are the most common pathogens?

-streptococcus pneumoniae

-haemophilus influenzae

-moraxella catarrhalis

What is tympanosclerosis?

white shale-like plaques on the TM and deposits on ossicles, which result in stiffening the TM and impedes movement

What is adhesive otitis media?

a form of chronic otitis media where there is an adhesion of the middle ear structures as a result of chronic inflamation

What causes facial paralysis?

VII cn passing through a section of the middle ear- if the toxic effects of the fluid errode a section of ME, then the VII nerve can be exposed and paralysis can occur

How do you manage OME

-administration of antimicrobial agents

-antihistamines and decongestants

-surgeries

What do bone conduction hearing aids do?

vibrate the skull to activate the cochlea

What is osteosclerosis?

a disorder in which there is formation of new bone around the foot plate of stapes, resulting in progressive conductive hearing loss

What is a stapedectomy?

a tiny plastic or steel strut that completely replaces the removed stapes

What is osteogenesis imperfecta?

a genetic disorder also know as brittle bone disease, that mainly affects the development of bones

what is barotrauma?

physical damage to body tissues caused by a difference in pressure between gas space inside the body and the surrounding gas or fluid

What are the two types of hearing loss?

1. conductive hearing loss

2. sensorineural hearing loss 

What is conductive hearing loss?

hearing impairment that occurs when sound waves are unable to pass through the outer and middle ear structures to reach the inner ear

What is sensorineural hearing loss?

hearing loss that occurs when the hair cells in the inner ear (cochlea) or the auditory nerve are damaged. 

Disorders of the outer and middle ear cause what?

conductive hearing loss

Disorders of the cochlea cause what?

the “sensori” part of “sensorineural”

Disorders of the VIII cn cause what?

the “neural” part of “sensorineural”

What is ototoxicity?

the term used to describe hearing loss caused by chemical agents

What is vestibulotoxicity?

damage to the vestibular system, which is responsible for balance and spatial orientation

What is acquired hearing loss?

hearing loss that develops after birth

What are synergistic effects?

two or more agents that work together to cause more of a problem/loss/disorder than any one of the agents alone would cause by itself

What are ototoxins?

chemicals or agents that are toxic to the auditory system and effect hearing and/or balance

What do aminoglycosides do?

treat gram-negative aerobic bacteria

What are the “Mycin” drugs?

-streptomycin

-gentamycin

-kanamycin

-tobramycin

What do chemotherapeutic drugs do?

treat cancers/destroy cancer cells

eg: cisplatin, carboplatin

What is serial monitoring of hearing?

the practice of tracking changes in a person's hearing over time by repeatedly performing hearing tests

What are loop diuretics? 

drugs that increase urine flow and cause diuresis

What is presbycusis?

a usually gradual, frequently bilateral sensorineural hearing loss related to the damage caused by the affects of aging in the inner ear

What are the symptoms of presbycusis?

• other peoples voices sounding mumbled or slurred

• can’t hear high pitched sounds

• men’s voices are easier to hear than women’s

What does decussate mean?

to cross over

What does ipsilateral mean?

on the same side of the body

What does contralateral mean?

on opposite sides of the body

What is a noise notch?

a characteristic "dip" on an audiogram that indicates hearing loss, often caused by exposure to loud noise

What does bilateral mean?

hearing loss in both ears

Right ear advantage

The right ear’s strongest pathway decussates across to the left hemisphere of the brain, where the primary and secondary auditory cortex is. The left ear’s strongest pathway
decussates across to the right hemisphere of the brain, then the neural activity has to pass back across the corpus callosum to get to the left hemisphere to be processed as speech and language.