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  #1  
Old 11-09-2012
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Neuro Visual Pathway Lesion

Assume a pt. have a lesion in Right inferior Meyer's loop..what are the pupillary changes seen when light is shown into the Left eye..?

a) direct reflex +ve and indirect reflex -ve
b) direct reflex +ve and indirect reflex +ve
c) direct reflex -ve and indirect reflex -ve
d) direct reflex -ve and indirect reflex +ve
e) cannot be interpreted from the given data..
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  #2  
Old 11-09-2012
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bbbbbb????
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Old 11-09-2012
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My answer is B. as meyers loop lesion causes contralateral sup quadrinopina only.
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Old 11-09-2012
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B .. Meyers loop is present after it gives away branches to the pretectal nucleus ..
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Old 11-09-2012
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nice question.. I choose B
thanks
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Old 11-09-2012
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Quote:
Originally Posted by venky2600 View Post
Assume a pt. have a lesion in Right inferior Meyer's loop..what are the pupillary changes seen when light is shown into the Left eye..?

a) direct reflex +ve and indirect reflex -ve
b) direct reflex +ve and indirect reflex +ve
c) direct reflex -ve and indirect reflex -ve
d) direct reflex -ve and indirect reflex +ve
e) cannot be interpreted from the given data..
b...Pupillary light reflex direct and indirect might not be affected in Mayer' loop lesion.
lesion of Rt .inf.Meyer's loop:lt.superior quadrantanopia
As VENKY has putforth this quest,might be tricky one...waiting for correct reply with explanation
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  #7  
Old 11-09-2012
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I am stuck between A and B
nice Qs, what is the source of the Qs?
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Old 11-09-2012
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Correct Answer b is the answer

the correct answer is B) both direct and indirect reflex +ve

@trupti---thanks ,this is not tricky q's like my previous ones

@fuser00----thanks, sorry it's not from any of the qbank i knew, i prepared the question..

it's very easy to answer these questions if you know the eye pathway well..

pupillary reflex----->when a light is shown into a eye,then it activates via 2nd nerve(afferent)--> the edinger westphal nuclei(efferent--3rd nerve--bilaterally),so both pupils will constrict(miosis)...
direct reflex is the reflex seen in the eye you showed the light(i/l)
indirect/concensual reflex is the reflex seen in the opposite eye(c/l) when the light is shown in the other one...

ex--->if light is shown in rt.eye------rt. eye constrict(direct+ve) and lt. eye constrict too(indirect reflex+ve)....




so from this.....there are only 3 defects can be seen in pupillary pathways............(from visual pathway)

1.
optic nerve damage/afferent defect(e.g--marcus gunn)----->so, if rt. optic nerve is damaged , both direct and inderect reflex -ve if light is shown in rt. eye...
both direct and indirect +ve if light is shown in lt. eye.....
summary--->rt. eye show no pupillary changes(in opposite eye too no change)

2. if 3rd nerve nuclei /efferent defect----->no efferent signal---> so, if rt.3rd nerve nuclei damages----->no efferent from 3rd n.
rt.eye----->direct reflex -ve but indirect reflex +ve
lt.eye----->direct reflex +ve but indirect reflex -ve
summary---> rt. eye has no pupillary changes..(can see change in opposite eye)


3. any pathway leaving them(optic tracts /optic radiations)-----
if rt. sided lesion
rt. eye-->both direct and indirect reflex+ve
lt. eye---->both direct and indirect +ve
summary--->no pupillary changes seen in between(coz, crossing over occurs at optic chiasm,which eliminates pupilaary changes)

here the question asks abt. 3rd scenario........so B is the answer..


hope it understands

thanks
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  #9  
Old 11-09-2012
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@venky2600
am sorry to draw you back but pls,there was a question posted here recently about a marathon runner and type of muscle fibers she has.. right?

you guys said it was a red fibre with high myoglobin?

am a little confused cause i just saw in my note,but cant remember where i copied it from that
(!)splinters legs,hands,extra ocular muscle fibers etc are type 2 white fibers with low myoglobin/mitochondria content.

i looked for that question but cant find it.What do you think?is my note wrong cos am not sure how i got it
thanx alot for always helping out
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Old 11-09-2012
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Quote:
Originally Posted by blade View Post
@venky2600
am sorry to draw you back but pls,there was a question posted here recently about a marathon runner and type of muscle fibers she has.. right?

you guys said it was a red fibre with high myoglobin?

am a little confused cause i just saw in my note,but cant remember where i copied it from that
(!)splinters legs,hands,extra ocular muscle fibers etc are type 2 white fibers with low myoglobin/mitochondria content.

i looked for that question but cant find it.What do you think?is my note wrong cos am not sure how i got it
thanx alot for always helping out
hey

dont feel sorry dude........ya i answered for your doubt in it.....your explanation is correct in it,but the answer should be red fibers...
Marathon versus 100-Yard Muscle Physiology!

hope this clears
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  #11  
Old 11-26-2012
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lesion in mayer loop nothg to do with reflex..so b
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