Becoming familiar with the Outer Becoming familiar with the Outer EarEar

The human auditory system can be The human auditory system can be divided into two sub-systems. divided into two sub-systems.

They are:They are:

1.1. The peripheral auditory systemThe peripheral auditory system

2.2. The central auditory systemThe central auditory system

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

The peripheral auditory system is The peripheral auditory system is further divided into three segments:further divided into three segments:

1.1. The outer earThe outer ear

2.2. The middle earThe middle ear

3.3. The inner earThe inner ear

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

The central auditory system consists of The central auditory system consists of the the neural pathwaysneural pathways from the from the cochlearcochlear nucleusnucleus to the to the auditory cortexauditory cortex located in located in the temporal lobe of the brain. the temporal lobe of the brain.

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

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

The development of the outer ear begins The development of the outer ear begins before the second fetal month. The before the second fetal month. The annulus for the tympanic membrane is annulus for the tympanic membrane is formed in the third fetal month.formed in the third fetal month.

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

The Auricle or Pinna is the soft tissue The Auricle or Pinna is the soft tissue forming a cup to the entrance of the forming a cup to the entrance of the external auditory meatus (ear canal)external auditory meatus (ear canal)

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

It is very important to learn the It is very important to learn the “landmarks” of the auricle/pinna“landmarks” of the auricle/pinna

(ref. Lass & Woodford page 51).(ref. Lass & Woodford page 51).

Many of these “landmarks” will be Many of these “landmarks” will be routinely used in your daily clinic routinely used in your daily clinic practice.practice.

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

The adult external auditory meatus The adult external auditory meatus is about an one and one-half is about an one and one-half inches long and generally and S inches long and generally and S shape.shape.

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

Between the sound collection of the Between the sound collection of the Pinna and the shape of the ear canal, Pinna and the shape of the ear canal, there is a natural peak acoustic there is a natural peak acoustic resonance of about 15 decibels at resonance of about 15 decibels at 2700Hz.2700Hz.

Note: This resonance is variable from ear to ear.Note: This resonance is variable from ear to ear.

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

The ear canal can be described in two The ear canal can be described in two distinct portions. They are:distinct portions. They are:

1.1. The cartilaginous portion (closest to the The cartilaginous portion (closest to the opening of the ear canal).opening of the ear canal).

2.2. The bony portion (closest to the The bony portion (closest to the typmanic membrane/eardrum).typmanic membrane/eardrum).

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

In the cartilaginous portion, you have In the cartilaginous portion, you have two sets of glands and also hair two sets of glands and also hair folliclesfollicles. .

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

The sebaceous glands produce oil. The sebaceous glands produce oil.

The ceruminous glands produce wax.The ceruminous glands produce wax.

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

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

Otoscopic viewing of the adult ear canal Otoscopic viewing of the adult ear canal requires requires pulling up and backpulling up and back on the pinna on the pinna to straighten the ear canal for to straighten the ear canal for observation of both it and the eardrum.observation of both it and the eardrum.

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

The view of the eardrum is broken into The view of the eardrum is broken into four quadrants. It is important to four quadrants. It is important to remember these four quadrants as you remember these four quadrants as you will use them often in writing will use them often in writing patient/client reports.patient/client reports.

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

The four quadrants are:The four quadrants are:

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

2.2. Anterior superiorAnterior superior

3.3. Posterior superiorPosterior superior

4.4. Posterior inferiorPosterior inferior

(ref. Lass & Woodford page #54)(ref. Lass & Woodford page #54)

Becoming familiar with the Outer Becoming familiar with the Outer EarEar

Becoming familiar with the Outer Becoming familiar with the Outer EarEar