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Med Neuro2 Lect5
Med Neuro2 Lect5 Auditory System I
Question | Answer |
---|---|
Describe briefly the 3 categories for the Glasgow Coma Scale? | 1.Best Eye Response (1-4). 2.Best Verbal Response (1-5). 3.Best Motor Response (1-6). **3 is the worst, 15 is the best. |
Frequency of a sound waves measures what two components? | 1.Compression event. 2.Rarefaction event. |
What is the normal human range of frequency? (in Hz) | 20Hz - 20KHz. **Presbycusis: this range narrows w/ age |
When we lose our hearing with age, which end of the frequency range goes first? | HIGH frequency (20KHz). |
What is the normal human range of amplitude (intensity)? | 0dB - 140dB. **0 dB represents the average threshold for humans. |
If someone had less sensitive hearing, would their acoustic spectrum start above or below 0 dB? more sensitive hearing? | LESS: Above at 20-30dB. MORE: Below at -10dB. |
As supported by an acoustic spectrum, what occurs as the frequency of sound increases? | It requires less intensity (amplitude) for us to hear it. **unless it is on the higher end of the freq range. |
At what frequency range is the lowest intensity (amplitude) required for hearing? What does this range represent? | 3000-5000 Hz. This is conversational speech. **represents MAX sensitivity |
Important External ear structures in localizing the sound wave on the TM? | 1.Pinna (asymmetric). 2.External ear canal. |
Important Middle ear structures in transmitting the energy of the sound wave from the external ear to the inner ear? | 1.TM 2.Ossicles. 3.Oval window (connected to Stapes). 4.Round Window (allows energy to dissapate) |
Damage to External & middle ear structures will most likely result in which type of hearing loss? | CONDUCTIVE |
Does a hearing Aid help a pt with conductive or sensorineural hearing loss? | CONDUCTIVE |
What change to the basilar membrane will be seen with high atmospheric pressure? low pressure? what structure helps prevent this? | HIGH: stapes will press into oval window, bowing the basilar membrane in. LOW (rainy front):stapes will pull out/away from the oval window pulling the basilar membrane towards it. **Helicotrema is a hole that will allow fluid to adjust. |
High auditory frequencies will stimulate which part of the basilar membrane? | The Base, which is stiffer, thicker, and more narrow. |
Low auditory frequencies will stimulate which part of the basilar membrane? | The Apex, which is softer, thinner, and wide/broad. |
What is the Modiolus? | The center of the spiraling cochlea which contains the acoustic nerve CN VIII. It will send branches off on each basilar membrane to connect to the Organ of Corti |
3 main chambers within the spiral cochlea? what is contained within them? | 1.Scala Vestibularis. 2.Scala Tympani. 3.Scala Media. **1&2 contain PERIlymph w/ low K+ & high Na+. **3 has EDNOlymph high K+ and low Na+. |
What does the Basilar membrane seperate? the Reissner's membrane? | 1.Basilar: the Scala Tympani from the Scala media. 2.Reissner's: The Scala vestibular from scala media. The Scala Vestibuli & tympani merge at the apex |
What important structure is contained within the Scala Media (located b/w the reissner's & basilar membranes)? | Organ of Corti |
Which membrane moves about the other within the spiral canals that creates the shearing forces on the stereocilia? | Basilar Membrane moves about the Tectorial membrane (which is attached to bone). |
What plate associated with the Organ of Corti houses the stereocilia so they can interact with the tectorial membrane? | Reticular lamina/plate |
B/w what two structures does the Basilar membrane spane across to seperate Scala Tympani perilymph from Scala media endolymph? | 1.Spiral Ligament. 2.Spiral Lamina (fanning off the modiolus). |
Key components of the organ or Corti (key auditory structure) | 1.Tectorial membrane. 2.Outer hair cells. 3.Inner hair cells. 4.Support cells. 5.Pillar cells (outer & inner). 6.Tunnel of Corti. 7.Auditory nerve fibers. |
What are the 3 main componentes of sensorineural hearing? | 1.Organ of Corti. 2.Fluid Movement & Basilar membrane. 3.CN VIII within the modiolus. |
Differentiate the 2 potential results from a Weber Test (place a tunning fork on center of pt's head) | 1.Conductive Loss: Sound Inc markedly in the ear with the reduced hearing. 2.Senorineural Loss: Sound Inc markedly in the ear with normal hearing. |