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Cards In This Set
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The Ipsilateral Ascending Pathway is?
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Ascending or afferent pathways- ARROW GOING UP
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The Ipsilateral or ascending Pathways are located where?
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First order neurons of the Cochlear 8th nerve divide just prior to entering the dorsal and ventral cohlear nuclei at the level of the medulla near the spinal cord.
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One part of the division enters the dorsal part of the cochlear nucleus and the other part where?
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The other part enters the ventral part of the cochlear nucleus THE FIRST ORDER NEURONS ALL SYNAPSE at this level.
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The Second Order Neurons?
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The second order neurons travel upward in the CANS via 2 routes
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These 2 routes are:
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The first route is from the dorsal cochlear nucleus soem fibers travel to the Superior Olivary Complex (SOC) which is at the same level of the CNS but more centrally located
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The second route
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The second route takes place from the dorsal cochlear nucleus other fibers travel to the nucleus of the lateral lemniscus (NLL) at the level of the PONS
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From the Superior Olivary Nucleus
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From the Superior olivary nucleus second and third order neurons travel to the nucleus of the lateral lemniscus Some fibers do not synapse in the superior olivary nucleus
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From the nucleus
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From the nucleus of he lateral lemniscus second third and fourth order nurones travel to the inferior colliculus on the level of the midbrain where some of the neurons make further synapses
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From the inferior colliculus
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Form the inferior colliculus fibers travel to the medial geniculate body at the level of the thalamus where all fibers terminate and synapse
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The contralateral ascending pathway
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The contralateral ascending pathway carries in the neighborhood of 2/3 of the fibers which reach the cortex from the ear while about 1/3 of the fibers ascend ipsilateral tract the crossed or contralateral fibers seem to be much more responsible for speech intelligibility than the ipsalateral fibers
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HISTORY OF HEARING THEORY
UNDERSTANDING COCHLEAR FUNCTION IS ESSENTIAL TO UNDERSTANDING COCHLEAR DYSFUNCTION
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CONVERSELY MISUNDERSTANDING COHLEAR FUNCTION RESULTS IN MISUNDERSTANDING OF COCHLEAR DYSFUNCTION AND THUS A MISUNDERSATNDING OF SENSORINEURAL HEARING LOSS
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HELMHOLTZ PRE 1940'S
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The mechanical resonant elements is what were responsible the cochlea performs spectrecal analisys
of the incoming signal
and that is how we distinguish those different sounds
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GEORGE von BEKESY 1940-1970's
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HE USED CADAVERS and models to develop
THE TRAVELING WAVE THEORY
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BEKESY BELIVED THE COCHLEA OR THE INNER EAR WAS
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LINEAR- THE INPUT VS THE OUTPUT
PASSIVE-NOT TRUE THE MIDDLE EAR IS PASSIVE SORD OF
BROADLY TUNED-
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IN THE LATE 1940'S THOMAS GOLD AN ENGHLISH PHYSICIST WAS PUZZLED ABOUT CERATIN ATTRIBUTES OF THE HEARING MACHANISM THAT IS
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HIGH SENSITIVITY
SHARP FREQUENCY TUNING-NARROW TUNED
WIDE DYNAMIC RANGE OF HEARING- THE COCHLEA CAN HEAR EXTREMELY SOFT SOUNDS
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