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.