Outer Ear

What are the parts of the peripheral auditory system?

1. Outer Ear

2. Middle Ear

3. Inner Ear

What does the Outer Ear consist of?

• Pinna

• External auditory canal

Pinna

Comprised of skin + cartilage

Tympanic Membrane

Located at the end of the external auditory canal

What are the major landmarks of the Pinna?

• Helix

• Antihelix

• Lobe

• Triangular fossa

• Cymba concha

• Crus of helix

• Cavum concha

• Antitragus

• Tragus

• Intertragal notch

Characteristics of the external auditory canal

• Curved ‘S’ shaped

• Stretches from pinna to tympanic membrane

• 1/3 is cartilaginous

• 2/3 comprised of bone

Function of the Pinna

• Sound enhancement

• Localizations

What is the resonant frequency an adult can hear?

2700-3400 Hz

Function of the external auditory canal

• Channel acoustic energy to the eardrum

• Produce cerumen

• Protect the eardrum 

• Serves as a resonator with one closed end

Function of the Outer Ear

• Enhance certain frequencies

• Protect

• Aid in localization

Anotia

Location: Pinna

• Absent pinna

Microtia

Location: Pinna

• Small pinna with or without landmarks

Perichondritis

Location: Pinna

• Infection of tissue surrounding cartilage

  • Bacterial infection with swelling

  • Redness

  • Pain

Preauricular fistula

Location: Pinna

• Depression in skin

• Anterior to helix + superior to tragus

Stenosis

Location: External Auditory Canal

• Narrowing of the external auditory canal 

External otitis

Location: External Auditory Canal

• AKA ‘swimmer’s ear’

  • Possible fever +/or drainage from external auditory canal 

  • Likely pain

  • Swelling of pinna

Otomycosis

Location: External Auditory Canal

• Fungal infection

  • Itching

  • Possible pain

  • Burning

  • Discharge

  • Hearing loss

Cerumen impaction

Location: External Auditory Canal

• Ear wax

  • Decrease in hearing

Localization

• Knowing the direction of a sound source in the horizontal plane

• High frequency differences between ears also help us locate sound sources in different planes (front, above, back)

Sound enhancement resonant frequency

1500 Hz or 1.5 kHz

What is the cause of Anotia?

• Congenital (present at birth)

• May be associated with a syndrome

What is the cause of Microtia?

• Congenital 

• May be associated with a syndrome

What is the cause of Perichondritis?

• Skin Conditions

What is the cause of Preauricular fistula?

• Congenital

• Disruption during development

What is the cause of Stenosis?

• Age

• Or may be congenital

What is the cause of External Otitis?

• Bacterial or fungal infection

• Humid Environment

• Skin Condition

• Trauma/abrasion

What is the cause of Otomycosis?

• Skin conditions

• Humid Environments

What is the cause of Cerumen?

• Hearing aid use

• Narrow ear canals

• Cotton swab use

What is the treatment for Anotia?

• Possible surgical reconstruction

• Amplification if indicated

What is the treatment for Microtia?

• Possible surgical reconstruction

• Or amplification if indicated

What is the treatment for Perichondritis?

• Antibiotics

What is the treatment for Preauricular?

• Antibiotics if infection/discharge

What is the treatment of Stenosis?

• Possibly surgery if linked to hearing loss

What is the treatment of External Otitis?

• Prescribed ear drops

What is the treatment of Otomycosis?

• Prescribed ear drops

What is the treatment of Cerumen?

• Cerumen removal with suction or curette