1. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
The human auditory system can beThe 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
2. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
The peripheral auditory system isThe 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
3. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
The central auditory system consists ofThe central auditory system consists of
thethe neural pathwaysneural pathways from thefrom the cochlearcochlear
nucleusnucleus to theto the auditory cortexauditory cortex located inlocated in
the temporal lobe of the brain.the temporal lobe of the brain.
Note:Note: We will have further discussion of theWe will have further discussion of the
central auditory system in the future.central auditory system in the future.
4. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
The development of the outer ear beginsThe development of the outer ear begins
before the second fetal month. Thebefore the second fetal month. The
annulus for the tympanic membrane isannulus for the tympanic membrane is
formed in the third fetal month.formed in the third fetal month.
5. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
The Auricle or Pinna is the soft tissueThe Auricle or Pinna is the soft tissue
forming a cup to the entrance of theforming a cup to the entrance of the
external auditory meatus (ear canal)external auditory meatus (ear canal)
6. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
It is very important to learn theIt 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 beMany of these “landmarks” will be
routinely used in your daily clinicroutinely used in your daily clinic
practice.practice.
9. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
The adult external auditory meatusThe adult external auditory meatus
is about an one and one-halfis about an one and one-half
inches long and generally and Sinches long and generally and S
shape.shape.
10. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
Between the sound collection of theBetween 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 acousticthere is a natural peak acoustic
resonance of about 15 decibels atresonance 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.
11. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
The ear canal can be described in twoThe ear canal can be described in two
distinct portions. They are:distinct portions. They are:
1.1. The cartilaginous portion (closest to theThe cartilaginous portion (closest to the
opening of the ear canal).opening of the ear canal).
2.2. The bony portion (closest to theThe bony portion (closest to the
typmanic membrane/eardrum).typmanic membrane/eardrum).
12. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
In the cartilaginous portion, you haveIn the cartilaginous portion, you have
two sets of glands and also hairtwo sets of glands and also hair
folliclesfollicles..
13. Becoming familiar with the OuterBecoming 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 protectThe hair, oil, and wax all serve to protect
the ear canal and eardrum from foreignthe ear canal and eardrum from foreign
materials.materials.
14. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
Otoscopic viewing of the adult ear canalOtoscopic viewing of the adult ear canal
requiresrequires pulling up and backpulling up and back on the pinnaon the pinna
to straighten the ear canal forto straighten the ear canal for
observation of both it and the eardrum.observation of both it and the eardrum.
15. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
The view of the eardrum is broken intoThe view of the eardrum is broken into
four quadrants. It is important tofour quadrants. It is important to
remember these four quadrants as youremember these four quadrants as you
will use them often in writingwill use them often in writing
patient/client reports.patient/client reports.
16. Becoming familiar with the OuterBecoming familiar with the Outer
EarEar
The four quadrants are:The four quadrants are:
1.1. Anterior inferiorAnterior 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)
