Special Senses Lecture 3 Flashcards
What are the 3 Ossicles?
Malleus, Incus, and Stapes
How does Cerumen protect the ear?
It has a bactericidal effect on some strains of bacteria due to presence of fatty acids, lysozyme and its acidity
How do hairs in the external auditory meatus protect a person?
They alert the individual when move by invaders to take steps to remove it
What does the Pinna do?
Funnels sound into the external auditory meatus
What does the External Auditory Meatus do?
Gathers sound energy and focuses it on the tympanic membrane which increases sound energy
What is the middle ear filled with?
Air
What is the major function of the Middle ear?
Match relatively low impedance airborne sounds to the higher impedance fluid of the inner ear
What are the two ways that sound is boosted by the middle ear?
- A differential of a large diameter tympanic membrane to a smaller diameter oval window
- Lever action of the ossicles
What does the Eustachian tube do?
Connects the middle ear to the pharynx to allow for the equalization of pressure
What are the muscles of the middle ear?
- Tensor tympani
* Stapedius muscle
What does the Tensor Tympani attach to?
The malleus and the eustachian tube
What does the Stapedius attach to?
The wall of the middle ear and neck of stapes near the articulation with the incus
What is the role of the Tensor Tympani and the Stapedius muscle?
Dampen the vibration of the ossicles
What are the Semicircular canals involved in?
Balance
What occurs in the cochlea?
Sound is processed
What is the inner ear composed of?
The cochlea
How many turns does the cochlea have?
2.75
From top to bottom what are the spaces of the cochlea?
- Scala Vestibuli
- Cochlear duct
- Scala Timpani
What is the top compartment of the Cochlea?
Scala Vestibuli
What is the middle component of the Cochlea?
The Cochlear duct
What is the bottom compartment of the Cochlea?
The Scala Tympani
Which components of the Cochlea are filled with Perilymph?
Scala vestibuli and Scala Tympani
What is the Cochlear duct/ Scala media filled with?
Endolymph
What separates the Scala Vestibuli and the Cochlear duct?
Reissner’s membrane
What does Reissner’s membrane separate?
Scala vestibuli and Cochlear duct
What does the Basilar membrane separate?
The cochlear duct and the Scala Tympani
What separates the Cochlear duct and the Scala Timpani?
The Basilar Membrane
What in the cochlea are one tube joined?
The Scala vestibuli and scala tympani
How are the Scala Vestibuli and Scala tympani joined?
With the Helicotrema
Where does the Organ of Corti rest?
On the Basilar Membrane
What do the inner hair cells do?
Encode for sound
What do the Outer hair cells do?
Help with sound frequency analysis, motor function
How many rows of outer hair cells are there?
3 rows
What do all hair cells have on top?
Stereocilia
What are Stereocilia?
Hair like bristles of varying length with the shortest in front and tallest in back on top of hair cells
What are Stereocilia attached to?
The Tectorial membrane
Where does the Tectorial Membrane sit?
On top of the stereocilia of hair cells
Which ion is the endolymph saturates with?
Potassium
What occurs during mechanical stimulation of the hair bundle?
Potassium ions from the endolymph depolarize the cell when the hair tips and tip links open creating action potentials
Where do high frequencies cause maximal dispacement?
Near the stapes
Where do low frequencies cause maximal displacement?
Near the apex
What is the function of the Round Window?
Dissipate sound energy
