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tompat
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05/29/07 - 11:24 PM

A tumor in the floor of the 4th ventricle has compressed the abducens nucleus in the dorsal part of the pons on the right. your pt exhibits an internal strabismus. what else u might expect you to see in the patient?
1.an ability to voluntarily look to the left with either eye.
2.an inability to wrinkle the forehead on the right
3. a snesorineural hearing loss
4.alteration of taste on the anterior 2/3 rds of the tongue
5.a right ptosis.
( yah ur right but help me to rule out the other option sad

)

Jackofknives
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05/30/07 - 12:30 AM

2

CN7 has an intern genu coursing around the CN6 nucleus, i.e. compression of the CN6 nucleus posteriorly is very likely to compress the CN7 nerve as well, result in Bell's palsy.

I posted the same question here a while ago.

Edited by Jackofknives on 05/30/07 - 01:09 AM

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tompat
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05/30/07 - 01:58 AM

what about option 1

tompat
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05/30/07 - 02:00 AM

when left cr.n.6 is stimulated it will contract left lat.rectus and also right med.rectus so pt will be able to see on left side voluntarily

Jackofknives
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05/30/07 - 03:39 AM

see

http://www.prep4usmle.com/forum/thread/53569

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There are many things in this world that can’t be changed no matter how hard you try. That’s why you must not hesitate when the time comes where you have to give it all you’ve got.

tompat
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05/30/07 - 04:38 AM

hey in this thread u talked about inability to look to left with either eye, but the option is ability to look to left with either eye

tompat
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05/30/07 - 05:04 AM

jacko u also said in that thread that ant.2/3 rd of the tongue receives dual suppy by VII nerve? did i interprete it right?
but i think VII nucleus receives dual suppy by corticobulbar fibers ,well not completely though but i failed to understand if this tumor is pressing upon VI n nucleus it is bound to press on lmn of VII n and will definately affect the taste sensation on that side of ant.2/3 of tongue

Jackofknives
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05/30/07 - 05:10 AM

taste is not conducted by the nucleus of CN7 which is 100% motor. taste is conducted via n. solivatorius superior. this nucleus is related to vestibular nucleus which is pretty far away from CN6 nucleus.

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There are many things in this world that can’t be changed no matter how hard you try. That’s why you must not hesitate when the time comes where you have to give it all you’ve got.

tompat
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05/30/07 - 05:43 AM

i and jack agreed on this.
in the option given 1 and 2 are the right choices.
the 4 th choice alteration of taste sensation of ant.2/3 is not correct as thecr. n .VII fibers involved will be purely motor ones and nucleus solitarious which receives sensory afferents is far away from VI n nucleus.
hope it will give a better idea .

hanwin
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05/31/07 - 06:28 PM

#10

Good explanation. Thanks Jack.

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