SHS 221: Module 5 external ear

intro to audiology

Collects sound and directs it to the tympanic membrane.

What is the main function of the external ear?

Pinna (auricle) and external auditory meatus (ear canal).

What are the two parts of the external ear?

Auricle.

What is another name for the pinna?

Funnels sound into the ear canal.

What is the main function of the pinna?

Auricular cartilage.

What is the pinna made of?

The outermost curved ridge of the pinna.

What is the helix?

A cartilaginous thickening on the helix; it is dominantly inherited.

What is Darwin's tubercle?

the inferior end of the helix; it contains no cartilage.

What is the lobule (earlobe)?

A prominent ridge of the pinna.

What is the antihelix?

the lower border of the concha bowl.

What is the antitragus?

A cartilage flap on the front wall of the ear canal.

What is the tragus?

It closes the canal and dampens unwanted sound.

What happens when you press on the tragus?

Around 5,000 Hz.

Around what frequency does the pinna collect sound most effectively?

Its irregular shape helps determine elevation and front/back location.

How does the pinna help locate sounds?

External auditory meatus, or ear canal.

What is the EAM?

An S-shaped tube, not a straight tube.

What shape is the ear canal?

To get a clearer view of the eardrum.

Why is the ear canal straightened during otoscopy?

Pull the ear up and back.

How is the adult ear canal straightened for otoscopy?

About 2.5–3.5 cm long.

How long is the ear canal?

About 0.65 cm wide.

What is the ear canal's approximate width?

About 0.9 cm high.

What is the ear canal's approximate height?

Cartilage.

What makes up the first 1/3 of the ear canal?

Bone from the temporal bone.

What makes up the remaining 2/3 of the ear canal?

Hairs, sebaceous glands, and ceruminous glands.

What is found in the cartilaginous ear canal?

In the cartilaginous portion of the ear canal.

Where is earwax (cerumen) produced?

Protects the ear canal by repelling water and removing dead skin.

What is one function of cerumen?

It discourages the growth of bacteria and fungi.

Why is cerumen slightly acidic?

It dries and falls out of the ear.

What normally happens to cerumen?

Temporary conductive hearing loss.

What can impacted earwax cause?

They can push earwax deeper into the canal and cause impaction.

Why can Q-tips cause hearing problems?

An acoustic resonator.

What does the ear canal act as?

About 5–20 dB.

How much can the ear canal boost sound?

About 1,500–7,500 Hz.

What frequency range does the ear canal boost?

Blocked sound and temporary conductive hearing loss.

What can a foreign object in the ear canal cause?

The adult canal runs slightly downward; a child's is more horizontal and shorter.

How does the adult ear canal differ from a child's?

An instrument used to examine the ear.

What is an otoscope?

Outer ear, middle ear, and inner ear.

What are the three major divisions of the ear?

Converts acoustic energy into mechanical movements.

What is the main function of the middle ear?

Converts mechanical movements into nerve impulses and helps maintain balance.

What is the main function of the inner ear?