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Discussion Starter · #1 ·
Can someone help me out with this question below...

A 64-year-old female patient is referred to a neurologist because her sister and brother both suffered recent strokes. She is diagnosed with an antiphospholipid antibody syndrome, a condition that causes hypercoagulation, and placed on warfarin. Despite the anticoagulation therapy she develops a thrombotic cerebral infarct, which leads to spasticity of her left wrist, elbow, and knee. The lesion most likely affected which of the following?

a. The corticospinal fibers
b. The vestibulospinal fibers
c. The Ia afferent fibers
d. The corticoreticular fibers
e. The reticulospinal fibers


Ok the answer is corticoreticular fibers but why not corticospinal fibers?? I thought UMN lesion's are the cause of spasticity due to damage in the corticospinal tracts?? ughhh... this neuro stuff!!! Please helpppp! :confused:
 

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Could not get it

What was the explanation given with the answer?
I can't get this question either.
Cortico-reticular tract is actually a part of the corticospinal tract as a whole as far as I know.
Involvement of the proximal muscles only may suggest cortico-reticular rather than corticospinal but the question is also mentioning wrist involvement which is not proximal.

Don't worry, you always get questions that are poorly constructed. In the real exam there won't be such questions, hopefully :(
 

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Discussion Starter · #3 ·
Hey Lee, yeah, there was an answer given, I actually got this from the Pre-Test Physiology book but I still dont get it even after reading the answer lol :eek: Here's what it said:


Spasticity results from overactivity of the a motoneurons innervating the skeletal musculature. Under normal circumstances, these alpha motoneurons are tonically stimulated by reticulospinal and vestibulospinal fibers originating in the brainstem. These brainstem fibers are normally inhibited by fibers originating in the cortex. Cutting the cortical fibers releases the brainstem fibers from inhibition and results in spasticity. Cutting the fibers from the reticular formation, vestibular nuclei, or the Ia afferents will reduce the spasticity.
 

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Hey Lee, yeah, there was an answer given, I actually got this from the Pre-Test Physiology book but I still dont get it even after reading the answer lol :eek: Here's what it said:

Spasticity results from overactivity of the a motoneurons innervating the skeletal musculature. Under normal circumstances, these alpha motoneurons are tonically stimulated by reticulospinal and vestibulospinal fibers originating in the brainstem. These brainstem fibers are normally inhibited by fibers originating in the cortex. Cutting the cortical fibers releases the brainstem fibers from inhibition and results in spasticity. Cutting the fibers from the reticular formation, vestibular nuclei, or the Ia afferents will reduce the spasticity.
Could not understand either!
Let's see if someone else can help us here...
 

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Corticoreticular fibers are one of the major output pathways from the motor cortex to the brainstem. They project widely and diffusely within the pontomedullary reticular formation. Such a diffuse projection pattern seems well suited to combining and integrating the function of the various types of reticulospinal neurons, which are widely scattered throughout the pontomedullary reticular formation. The corticoreticular-reticulospinal-spinal interneuronal connections appear to operate as a cohesive, yet flexible, control system for the elaboration of a wide variety of movements, including those that combine goal-directed locomotion with other motor actions.

hmmmm.....well every one will make mistake of selecting corticospinal tract...so do not worry about this kind of Qs....



but we can differntiate.....by "spasticity of wrist, elbow, and knee"
they hv not mentioned spasticity of whole limb....:rolleyes:.
 
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