Outer Ear
Oil glands can be found in which part of the EAM?
The outer 1/3. This is where cerumen (wax) is found and serves as protection and lubrication
What is the tense, inferior, 75% region of the Tympanic Membrane called?
Pars Tensa
Role of outer hair cells (2):
In the inner ear, ______ energy is converted to ______ energy
In the inner ear mechanical energy is converted to electrochemical energy
What helps hold the basilar membrane in place?
Spiral ligament
Spiral lamina
Spiral limbus
Modiolous
Spiral ligament
What are the components of the outer ear?
Pinna - (auricle) cartilage flap
Concha - The bowl-like cavity of the pinna
External Auditory Meatus (Ear Canal)
Tympanic Membrane (TM/ear drum)
Eustachian tube connects the _________ to an opening in the ______
What is it for?
air filled middle ear cavity to an opening in the upper back portion of the throat (nasopharynx) allowing air to come into the cavity
- what is it for? = equalize pressure between middle ear and outer ear
The round window is located at the base of which chamber?
The scala tympani
How can we distinguish outer hair cells from inner hair cells?
OUTER HAIR CELLS:
INNER HAIR CELLS
Which is a mound of connective tissue found in the scala media?
spiral limbus
What are the roles (4) of the outer ear?
What is attenuation? What is the purpose?
Attenuation is the tympanic reflex 40-80msec following a loud sound 85dB or more. It protects the cochlea
95% of the _______ fibers are from the inner hair cells
afferent fibers
The stereocilia of the OHC are embedded into its undersurface, and it projects from the spiral limbus
tectorial membrane
the ratio of ____ to ______ in the middle ear adds about ___dB of energy
the ratio of the TM to the oval window (17:1), boost the energy, and adds about 25dB of energy
Why do we want to maintain equal pressure between the outer and middle ear?
We want equal pressure between the middle and outer ear so that the TM can vibrate at the proper rate. The eustachian tube maintains this balance
3 characteristics of the middle ear minimize the loss of acoustic energy via impedance matching
1. Area ratio (area advantage)
2. lever action
3. Shape of tympanic membrane
Where can you find the organ of corti?
foiund within the Scala Media, rests on the basilar membrane
This membrane is wider at the apex and narrower at the base, runs the length of the cochlea, and is inferior to the Organ of Corti
Basilar Membrane
This brain synapse deals with spatial localization.
Superior olivary complex
What three components play a factor into protecting the ear?
Shape of the EAM
Cerumen (ear wax)
Hair follicles
What are the roles (3) of the middle ear?
Where can you find perilymph? Where can you find endolymph?
Scala vestibuli = perilymph
Scala media = endolymph
Scala tympani - perilymph
bony labrynth= perilymph, membranous labryinth = endolymph
When the basilar membrane moves UP, the hair cells shear towards _______
When the basilar membrane moves DOWN, the hair cells shear towards__________
Functions of the inner ear (name both vestibular and cochlear functions)
Vestibular system
Cochlea