Palaniappan
Forum Senior
Topics: 30
Posts: 148
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A patient suffers a stroke and presents with weak right limbs,a mandible that deviates to the left upon protrusion,and anaesthesia of the face and the scalp.Where is the lesion?
A.Pons
B.Trigeminal nerve
C.Posterior limb of Int.Capsule
D.Medulla
E.Paracentral lobule of the cortex
Please explain your answer
Thanx
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| alb123
Forum Newbie
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Posts: 34
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ah leasion.. lets see.. at first i almost selected pons, but it didnt fit the problem correctly.
I believe it is the medulla (D).
The medulla contains the nucleus of the trigeminal nerve. If an injury occurs here (on the right) the ipsalateral side of mastication muscles will be paralyzed and upon protrusion the jaw will move away from the paralysis (to the left). Also the face and scalp will experience some anaesthesia due to trigeminal nerve damage.
Cortico spinal tracts are passing through the medulla and also are injured.
This injury must have taken place after the corticospinal tract has already crossed allowing for ipsalateral hemiparesis.
I hope that i got that right with all the explanation i gave.. ??????? someone back me up please
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| Palaniappan
Forum Senior
Topics: 30
Posts: 148
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You are almost right alb123 ..except that the Motor and the sensory nucleus for the trigeminal nerve is in Pons and hence its lesion causes the protruded mandible to deviate to the ipsilateral side..Only the spinal motor nucleus of the V nerve is in the medulla.One nore-The mesencephalic nucleus of the V nerve is in the midbrain-Controls the proprioception adn the jaw jerk.
Whenever ,A ipsilateral cranial nerve is affected along with the contralateral tracts-it is BRAIN STEM lesion
Since,cranial nerve 5 has its nucleus in the pons ,the answer is A.
hope you might have wished to stick with your first answer
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| alb123
Forum Newbie
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yeah i mixed up the action of muscles that cause jaw protrusion (lateral pterygoid).. it was an easy question.. I was wondering why i couldnt make sense of "pons" it sounded right, just overthought it i guess.. feel free to post more questions..
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| Ancylostoma
Forum Guru
Topics: 42
Posts: 637
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Palani, the jaw deviation is due to the paralysis of the motor nucleus of the trigeminal. This nucleus is also found in the pons
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| Palaniappan
Forum Senior
Topics: 30
Posts: 148
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yeah..I think I have mentioned that :-)
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| mytimenow
Forum Senior
Topics: 12
Posts: 209
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palaniapan is right its pon
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