SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

The human auditory system can be

divided into two sub-systems.

They are:

1. The peripheral auditory system

2. The central auditory system

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

The peripheral auditory system is further

divided into three segments:

1. The external ear

2. The middle ear

3. The inner ear

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

The external ear is comprised of two parts.

They are:

1. The external auditory meatus (ear canal)

2. The auricle (pinna)

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

The Auricle or Pinna is the soft tissue forming

a cup to the entrance of the external auditory

meatus (ear canal)

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

There are two major contributions to the auditory system attributable to the external ear. They are:

1. It facilitates auditory sensitivity by providing a low-resistance path to the auditory mechanism.

2. The acoustic properties of the external auditory meatus serve to increase one portion of the frequency spectrum.

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

Between the sound collection of the Pinna and

the shape of the ear canal, there is a natural

peak acoustic resonance of about 15 decibels

at 2700Hz.

Note: This resonance is variable from ear to ear.

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

Perhaps a third contribution to the auditory system by the external ear is to provide information regarding the localization of a sound.

The difference between sound arrival and collection by the Pinna, offer enhanced information to assist with sound localization.

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

The characteristic landmarks of the

Pinna are important to remember.

Let’s review the more important

landmarks.

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

Helix

Scaphoid Fossa

Antihelix

Antitragus

Lobule

Tragus

Concha

Triangular Fossa

Intertragal Notch

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

The adult external auditory meatus is

about an one and one-half inches long

and generally and S shape.

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

The ear canal can be described in two

distinct portions. They are:

1. The cartilaginous portion (closest to the

opening of the ear canal).

2. The bony portion (closest to the typmanic

membrane/eardrum).

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

In the outer third (the cartilaginous

portion), you have two sets of glands

and also hair follicles.

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

The sebaceous glands produce oil.

The ceruminous glands produce wax.

The hair, oil, and wax all serve to protect the ear canal and eardrum from foreign materials.

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

Otoscopic viewing of the adult ear canal

requires pulling up and back on the

pinna to straighten the ear canal for

observation of both it and the eardrum.

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

The view of the eardrum is broken into

four quadrants. It is important to

remember these four quadrants as you

will use them often in writing

patient/client reports.

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

The four quadrants are:

1. Anterior inferior (where you find the cone of light)

2. Anterior superior

3. Posterior superior

4. Posterior inferior

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

SENSITIVITY & LANDMARKS OF THE EXTERNAL EAR

Let’s practice “getting acquainted” with

our otoscopes and ear canal inspection

process.