1 Hearing anatomy and Flashcards
(33 cards)
Which of the 3 parts of the ear is the location of most problems related to hearing loss?
The inner ear. Sensorineural is the most common type of hearing loss and it affects the inner ear.
What are the three parts of the human ear?
The three parts of the human ear are the outer ear, middle ear, and inner ear.
What psychological impacts are associated with untreated hearing loss?
Individuals with untreated hearing loss are more likely to report depression, anxiety, and paranoia and are less likely to participate in organized social activities compared to those who wear hearing aids.
What is the motivation for studying Biomedical Acoustics?
360 million individuals suffer from hearing loss worldwide with 6-8% of the world population affected. 91% are adults and 9% are children. 11000 newborns suffer from hearing loss. 50% of individuals aged 65 and older suffer from significant hearing loss and up to 95% of those aged 80 and older suffer from significant hearing loss.
What is the function of the outer ear?
The outer ear, also known as the external ear, consists of the pinna and the ear canal which transmit sound to the tympanic membrane (ear drum).
What are the characteristics of the ear canal?
The ear canal is about 4 cm long in adults and consists of outer cartilage and an inner bony part. The cartilaginous portion has hairy skin containing sweat glands and oily sebaceous glands that produce ear wax, which is a protective barrier and disinfectant.
What is the pinna’s structure and function?
The pinna collects sound and directs it into the ear canal. It is made of cartilage covered by skin and does not contribute to sound amplification.
It helps to localise sound
Why is the ear canal bent?
To protect against foreign bodies. The start is cartilaginous but the deeper part is bony and does not have the ability to migrate wax and foreign bodies.
What is cholesteatoma?
Cholesteatoma is an abnormal noncancerous skin growth in the ear that can destroy the delicate bones (ossicles) in the middle ear affecting hearing and balance. Treatment usually involves surgical removal.
What is the structure and function of the tympanic membrane?
The tympanic membrane is a thin layer of skin on the outside and a thin membrane of respiratory epithelium on the inner surface with a stiffening fibrous middle layer called pars tensa. It is less than 1/10th of a millimeter thick.
What is the middle ear?
The middle ear is an air-filled space that houses the malleus, incus, and stapes bones which conduct sound from the tympanic membrane to the inner ear.
What does the footplate of the stapes cover?
The oval window (opening to the cochlea).
What are the three bones of the middle ear?
The three bones of the middle ear are the malleus, incus, and stapes.
Which 2 sensory organs does the inner ear contain?
The inner ear contains the cochlea (hearing) and the vestibular system (balance).
What is the cochlea?
The cochlea is the inner ear organ shaped like a snail shell (2.5 turns) that houses the organ of hearing (organ of Corti) and is involved in sound perception.
What is the Eustachian tube and its function?
The Eustachian tube links the nose to the middle ear helping to equalize air pressure in the middle ear and the nose.
In adults it is approximately 35mm long and 3mm in diameter
What role do hair cells play in hearing?
Hair cells transduce vibrations into nervous impulses with inner hair cells responsible for transmitting signals to the brain and outer hair cells acting as amplifiers.
Where is the basilar membrane located?
The basilar membrane is located in the cochlea of the inner ear.
How many hair cells and nerve fibers does the inner ear contain?
30000 hair cells and 19000 nerve fibers.
What fluids fill the cochlea?
The cochlea contains two types of fluids: perilymph in the scala vestibuli and scala tympani and endolymph in the membranous labyrinth (scala media).
What is the normal human (newborn) hearing range (Hz)?
16 Hz to 20000 Hz.
Most sensitive to 128 Hz to 4000 Hz (range of human voice).
What is the relationship between sound frequency and cochlear response?
High frequencies deflect the base of the cochlear duct while low frequencies deflect the apex. Different parts of the cochlear duct respond to different sound frequencies (because of Basilar membrane).
How are hair cells arranged?
There are 4 rows of hair cells on top of the basilar membrane:
1 row of inner hair cells and 3 rows of outer hair cells. Inner hair cells have an abundant nerve supply (compared to outer cells).
