Transcript The Outer Ear - College of Liberal Arts and Sciences

The Outer Ear
SPA 4302
Summer 2007
Development of the Outer Ear
• About __________ after conception the
pharyngeal arches develop (bulges on the area of
the embryo that will later develop into the head
and neck)
• As many as ____ all separated by grooves and
clefts
• First three:
– __________ arch
– __________ arch
– ____________________ arch
Development of the Outer Ear
• Each of the arches has three layers
– _______________ (outer layer)
– _______________ (middle layer)
– _______________ (inner layer)
• Each arch contains four components:
– An artery, muscle and cartilage (from mesoderm)
– Nerve (from _______________)
• Aurical develops from the first 2 pharyngeal arches
• EAC develops from the first pharyngeal groove
• TM develops from ______________: inner layer
from endoderm, middle layer from mesoderm, and
outer layer from ectoderm
External Auditory Canal
• lateral portion-__________
• medial portion-_________
• lined with epidermal (skin)
tissue
• hairs grow in lateral part
• cerumen (ear wax) secreted
in lateral part.
• Usually curved.
Outer Ear Functions 1
• Amplification / Filtering
-- 1500 to 7000 Hz increased by ________________
-- produced by resonance of Concha (_______ kHz) &
E.A.Canal (_____________ Hz)
Outer Ear Functions 2
• Protection
-- medial displacement
of ___________
-- curvature of canal
-- _____________
-- cerumen
-- _____________
Outer Ear
Functions 3
Localization
-- The ability to
_________________
____ of a sound
source
Otoscopy
• Viewing outer ear and TM
Looking for:
• _____________,
• Evidence of infection
• Other __________
Lateral Process (Malleus)
= Annulus
Malleus
Manubrium
Umbo
Cone of Light
Epidermal migration produces
“wrinkles”
Disorders of the Pinna:
• Microtia- ___________________________
• Anotia- ____________________________
• Congenital malformation associated with
syndromes and disorders
• _____________- surgery performed to
correct a pinna that either protrudes
markedly from head or is pinned to closely
Disorders:
• Blockage: with earwax, foreign bodies, pus.
• Otitis Externa: ________________.
– Fungal or Bacterial in origin.
– More frequent in ears with small canal
• openings that cannot dry out as easily.
– This is also sometimes a problem for people
wearing _____________-.
Otitis Externa
Cerumen
A Cerumen Tunnel
Car Accident Victim
Who just didn’t “feel right” afterward…
Another Foreign Object
Exostoses: Benign bony growths in the outer
ear canal
• Contrast with
Osteomas
A False Tympanic Membrane
• A layer of dead
skin cells builds up
in persons who
use earplugs or
some hearing
aids frequently
Injuries to Ear Canal
A
Q-tip
Victim
Squamous Cell Cancer
Malformations: congenital,
traumatic or surgical.
• ______________: external ear is small,
malformed
• ______________: ear canal is closed off.
• Post-cancer surgery.
Congenital Malformation
Microtia
Anotia: Pre- and Post-Op
Mastoiditis
Hearing Loss accompanying
these disorders:
• Blockage or atresia:
– moderate ________________ hearing losses.
– usually medically or surgically treatable.
– additional HL if _______________--associated
problems w/ cochlea
• Surgical or traumatic:
– ___________- frequency conductive.
– prosthetics available, expensive.