Becoming familiar with the Outer Ear

The human auditory system can be

divided into two sub-systems.

They are:

1. The peripheral auditory system

2. The central auditory system

Becoming familiar with the Outer Ear

The peripheral auditory system is

further divided into three segments:

1. The outer ear

2. The middle ear

3. The inner ear

Becoming familiar with the Outer Ear

The central auditory system consists of the neural pathways from the cochlear nucleus to the auditory cortex located in the temporal lobe of the brain.

Note: We will have further discussion of the central auditory system in the future.

Becoming familiar with the Outer Ear

The development of the outer ear begins

before the second fetal month. The

annulus for the tympanic membrane is

formed in the third fetal month.

Becoming familiar with the Outer Ear

The Auricle or Pinna is the soft tissue

forming a cup to the entrance of the

external auditory meatus (ear canal)

Becoming familiar with the Outer Ear

It is very important to learn the

“landmarks” of the auricle/pinna

(ref. Lass & Woodford page 51).

Many of these “landmarks” will be

routinely used in your daily clinic practice.

Becoming familiar with the Outer Ear

Becoming familiar with the Outer Ear

Becoming familiar with the Outer Ear

The adult external auditory meatus

is about an one and one-half

inches long and generally and S

shape.

Becoming familiar with the Outer 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.

Becoming familiar with the Outer 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).

Becoming familiar with the Outer Ear

In the cartilaginous portion, you have

two sets of glands and also hair

follicles.

Becoming familiar with the Outer 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.

Becoming familiar with the Outer 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.

Becoming familiar with the Outer 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.

Becoming familiar with the Outer Ear

The four quadrants are:

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

2. Anterior superior

3. Posterior superior

4. Posterior inferior

(ref. Lass & Woodford page #54)

Becoming familiar with the Outer Ear

Becoming familiar with the Outer Ear