1. 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

2. 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

3. 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.

4. 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.

5. 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)

6. 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.

7. Becoming familiar with the Outer Ear

8. Becoming familiar with the Outer Ear

9. 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.

10. 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.

11. 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).

12. Becoming familiar with the Outer Ear
 In the cartilaginous portion, you have
two sets of glands and also hair
follicles.

13. 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.

14. 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.

15. 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.

16. 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)

17. Becoming familiar with the Outer Ear

18. Becoming familiar with the Outer Ear