Term
| Auditory and vestibular receptors are located _______ |
|
Definition
| In the inner ear, deep inside the temporal bone. |
|
|
Term
| The bony labyrinth houses the _______. |
|
Definition
Auditory and vestibular sense organs.
-It consists of a series of cavities in the temporal bone. |
|
|
Term
| The membranous labyrinth lies where? |
|
Definition
In the bony labyrinth cavities.
-The membranous labyrinth generally follows the form of the bony labyrinth but is somewhat smaller. |
|
|
Term
| The membranous labyrinth is filled with a specialized fluid called ______, while another fluid, called ______, lies outside the membranous labyrinth in the space between the bony and membranous labyrinths. |
|
Definition
|
|
Term
| Each labyrinth (left and right)consists of: |
|
Definition
The auditory apparatus consists of the cochlea
b. the vestibular apparatus consists of two sets of sensory structures:
i. three semicircular canals or ducts
ii. a pair of otolith organs, called the utricle and the saccule |
|
|
Term
| Air-borne sound waves enter the auditory system via the outer ear and then through the ear canal or _______________. |
|
Definition
| External auditory meatus. |
|
|
Term
| The tympanic membrane is known as what? And does what? |
|
Definition
| Ear drum, separates the ear canal from the middle ear cavity. |
|
|
Term
| The middle ear, an air filled cavity that contains what three small bones? |
|
Definition
| Ossicles, called the malleus (hammer), incus (anvil), and stapes (stirrup). Together these ossicles provide the physical connection between the outer and inner ear. From the tympanic membrane, the vibration is conveyed to the malleus, then to the incus, and then to the stapes. |
|
|
Term
| Air pressure in the middle ear cavity is normally equal to or higher than the atmospheric pressure? |
|
Definition
| Is normally equal to atmospheric pressure because the auditory or eustachian tube connects the middle ear to the nasal cavity. |
|
|
Term
| The stapes is in contact with the __________, an opening in the cochlea |
|
Definition
|
|
Term
| The cochlea is a structure that spirals 2 1/2 turns in the inner ear, in the temporal bone, and has three fluid-filled compartments or scalae, which are: |
|
Definition
i. The scala vestibuli (filled with perilymph) located on the oval window side of the cochlear duct.
ii. The scala tympani (also filled with perilymph) which is continuous with the scala vestibuli at the helicotrema and is located on the round window side of the cochlear duct.
iii. The scala media, also called the cochlear duct, (filled with endolymph) lies between the two other scalae and extends into the cochlea. The cochlear duct houses the sensory receptors in a structure called the organ of Corti. |
|
|
Term
| The scala vestibuli (filled with perilymph) located on the... |
|
Definition
| oval window side of the cochlear duct. |
|
|
Term
| The scala tympani (also filled with perilymph) which is continuous with the scala vestibuli at the helicotrema and is located on the... |
|
Definition
| round window side of the cochlear duct. |
|
|
Term
| cochlear duct houses the sensory receptors in a structure called the... |
|
Definition
|
|
Term
| The hair cells of the organ of Corti, which sits on the basilar membrane, innervated by afferent and efferent axons (see below) of what nerve? |
|
Definition
|
|
Term
| Pressure waves of the _____ and the _____ set up oscillating movements of the scala media or cochlear duct. |
|
Definition
| The scala vestibuli and scala tympani |
|
|
Term
T or F
Yhe area of the tympanic membrane is greater than the area of the oval window? |
|
Definition
|
|
Term
| Stereocilia are located where? |
|
Definition
| on the apex of each hair cell are embedded in the overlying stiff tectorial membrane. |
|
|
Term
| When the stereocilia bend and undergo an angular displacement in relation to their fixed tips, what happens? |
|
Definition
Opens ion channels in the hair cells, and by flow of inward current carried by cations, generates a receptor potential in the hair cell.
The hair cell releases a chemical neurotransmitter which depolarizes the peripheral component of the auditory portion of CN VIII.
Action potentials are initiated in the axon of the bipolar neurons of the cochlear portion of the CN VIII.
The cell bodies of auditory CN VIII neurons lie in the spiral ganglion. Central processes terminate (synapse) in the cochlear nuclei in the medulla of the brainstem. |
|
|
Term
| The cell bodies of auditory CN VIII neurons lie in the |
|
Definition
|
|
Term
| High frequency sounds (~15,000 Hz) have their peak amplitude near the base of the... |
|
Definition
| cochlea (near the oval window |
|
|
Term
| Low frequency sounds (~100 Hz) have their peak amplitude near the... |
|
Definition
| apex (near the helicotrema) |
|
|
Term
| Are the hair cells along the organ of Corti are identical or not identical? |
|
Definition
| not identical and have different electromechanical properties which contribute to frequency selectivity. |
|
|
Term
| Hair cells at the base of the cochlea have stereocilia that are ___________ compared to hair cells at the apex, in which the stereocilia are _______. |
|
Definition
short & stiff
twice as long |
|
|
Term
| Action potentials traveling down the central process of the cochlear nerve reach the... |
|
Definition
| dorsal and ventral cochlear nuclei in the upper medulla. (These nuclei are tonotopically organized; tonotopic organization is maintained for the auditory pathway as a whole). |
|
|
Term
| Most fibers rom the dorsal and ventral nuclei decussate in the... |
|
Definition
| lower pons and ascend in the lateral lemniscus (lies lateral to the medial lemniscus). Some of those decussating fibers synapse on neurons in the superior olivary nuclear complex and some on neurons in the reticular formation. In addition, some fibers ascend uncrossed in the ipsilateral lateral lemniscus. Therefore, a unilateral lesion of the central auditory pathway causes more marked hearing loss on the side opposite the lesion. |
|
|
Term
| Fibers in the lateral lemniscus synapse in the __________, and from there, axons go on to the _________ of the diencephalon. |
|
Definition
inferior colliculus, medial geniculate
-Neurons in the medial geniculate send axons, called auditory radiations, to the primary auditory cortex located in the transverse temporal of gyri |
|
|
Term
| Functions of parts of the Central auditory pathway |
|
Definition
A. Primary auditory cortex – conscious hearing of sound
B. Superior Olivary Nucleus and Inferior Colliculus – orientation/localization of sound
C. Reticular Formation – CNS activation/alertness |
|
|
Term
| Primary auditory cortex responsible for: |
|
Definition
| conscious hearing of sound |
|
|
Term
| Superior Olivary Nucleus and Inferior Colliculus responsible for: |
|
Definition
| orientation/localization of sound |
|
|
Term
| Reticular Formation responsible for: |
|
Definition
|
|
Term
| descending efferent pathway from the cortex to the cochlea via CN VIII can... |
|
Definition
Can excite or inhibit cochlear activity.
A. Thought to be inhibitory than excitatory.
B. Through inhibition, it functions suppress extraneous noise and sharpen clarity of hearing. |
|
|
Term
| What muscle inserts into the malleus (innervated by CN V, trigeminal)and function is to dampen vibration of tympanic membrane in response to loud noise. |
|
Definition
|
|
Term
| What muscle inserts into the stapes (innervated by CN VII, facial) and function is to dampen vibration of stapes in response to loud noise. |
|
Definition
|
|
Term
| Conductive Deafness is caused by |
|
Definition
interruption of the passage of sound waves through the external or middle ear.
A. Obstruction by a foreign body in the external auditory meatus.
B. Otosclerosis (most frequent cause) is a result of fixation of the stapes, due to excessive bone growth of surrounding bony labyrinth.
C. Otitis media, an inflammation of the middle ear (i.e., middle ear infection--very common in children). This is also the most common cause of meningitis and the most common cause of brain abscesses. |
|
|
Term
|
Definition
| (most frequent cause) is a result of fixation of the stapes, due to excessive bone growth of surrounding bony labyrinth. |
|
|
Term
|
Definition
| an inflammation of the middle ear (i.e., middle ear infection--very common in children). This is also the most common cause of meningitis and the most common cause of brain abscesses. |
|
|
Term
|
Definition
also called nerve deafness or perceptive deafness). Causes include:
A. Disease of the cochlea, CN VIII, or the central auditory connections.
B. May result from action of drugs and toxins (quinine, aspirin, and streptomycin).
C. May result from rubella infection in utero, cytomegalovirus, and syphilis.
D. Presbycusis, or hearing loss that occurs with aging, results from degenerative disease of the organ of Corti, particularly at the base, resulting in reduced ability to hear high frequency sounds.
E. An acoustic neuroma (a schwannoma): a tumor of CN VIII. May be located in the cerebellopontine angle, near the brainstem exit of CN VIII. Results in unilateral deafness and tinnitus (ringing in the ear). |
|
|
Term
|
Definition
| hearing loss that occurs with aging, results from degenerative disease of the organ of Corti, particularly at the base, resulting in reduced ability to hear high frequency sounds. |
|
|
Term
|
Definition
| (a schwannoma): a tumor of CN VIII. May be located in the cerebellopontine angle, near the brainstem exit of CN VIII. Results in unilateral deafness and tinnitus (ringing in the ear). |
|
|
Term
|
Definition
Due to damage to CN V (trigeminal) or to the tensor tympani muscle, preventing this muscle from dampening sounds. Causes increased acuity of hearing and hypersensitivity to low frequency sounds
2. Due to damage to CN VII (facial), preventing the stapedius muscle from dampening sounds. |
|
|
Term
|
Definition
Abnormal sounds (ringing, hissing, roaring, buzzing, or humming)
2. Causes:
A. Acoustic neuroma
B. Irritation of spiral organ of Corti in the cochlea
C. Irritation of CN VIII
D. Overproduction of endolymph |
|
|
Term
| Meniere's Syndrome (Meniere's Disease) |
|
Definition
1. Due to overproduction of endolymph or inability to absorb endolymph--results in excessive quantities of endolymph (called endolymphatic hydrops)
2. Symptoms: tinnitus and vestibular disturbances (dizziness, vertigo, nausea, vomiting, nystagmus). |
|
|
Term
| Unilateral lesion of ascending auditory pathway causes |
|
Definition
| bilateral diminution of hearing, more marked on contralateral side (ascending pathway is mostly crossed fibers). |
|
|
Term
| Lesions of the auditory cortex do not disrupt the perception of sound frequency but do affect the ability to |
|
Definition
| localize sounds in space; i.e., our ability to process auditory information is impaired. |
|
|
