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Upper extremity muscle function and innervation 04

Topic: Anatomy

Created on Sunday, November 9 2008 by jdmiles

Last modified on Sunday, November 9 2008.

During a needle EMG of the upper extremity, you notice a large number of fibrillations in the pronator teres muscle while the patient is at rest. From this, you deduce that the patient has a lesion. Of the following options, which lesion is most compatible with the EMG findings?

 
        A) A C5 radiculopathy
 
        B) A lesion in the lower trunk
 
        C) A lesion in the posterior cord
 
        D) A C7 radiculopathy
 
        E) A cervical spinal cord lesion
 

 


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This question was created on November 09, 2008 by jdmiles.
This question was last modified on November 09, 2008.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ANSWERS AND EXPLANATIONS




A) a C5 radiculopathy

This answer is incorrect.


The fibrillations suggest an active peripheral nerve lesion. The pronator teres muscle receives innervation from the median nerve, the lateral cord, the upper and middle trunks, and the C6 and C7 nerve roots. The branch to pronator teres arises from the median nerve proximal to the origin of the anterior interosseous nerve.   (See References)

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B) a lesion in the lower trunk

This answer is incorrect.


The fibrillations suggest an active peripheral nerve lesion. The pronator teres muscle receives innervation from the median nerve, the lateral cord, the upper and middle trunks, and the C6 and C7 nerve roots. The branch to pronator teres arises from the median nerve proximal to the origin of the anterior interosseous nerve.   (See References)

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C) a lesion in the posterior cord

This answer is incorrect.


The fibrillations suggest an active peripheral nerve lesion. The pronator teres muscle receives innervation from the median nerve, the lateral cord, the upper and middle trunks, and the C6 and C7 nerve roots. The branch to pronator teres arises from the median nerve proximal to the origin of the anterior interosseous nerve.   (See References)

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D) a C7 radiculopathy

This answer is correct.


The fibrillations suggest an active peripheral nerve lesion. The pronator teres muscle receives innervation from the median nerve, the lateral cord, the upper and middle trunks, and the C6 and C7 nerve roots. The branch to pronator teres arises from the median nerve proximal to the origin of the anterior interosseous nerve.   (See References)

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E) a cervical spinal cord lesion

This answer is incorrect.


The fibrillations suggest an active peripheral nerve lesion. The pronator teres muscle receives innervation from the median nerve, the lateral cord, the upper and middle trunks, and the C6 and C7 nerve roots. The branch to pronator teres arises from the median nerve proximal to the origin of the anterior interosseous nerve.   (See References)

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References:

1. Preston, D.C., and Shapiro, B.E. (2005). Electromyography and Neuromuscular Disorders: Clinical-Electrophysiologic Correlations, 2nd Edition. Elsevier, Philadelphia. (ISBN:075067492X) Advertising:
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anatomy
Upper extremity muscle function and innervation 04
Question ID: 081808103
Question written by J. Douglas Miles, (C) 2006-2009, all rights reserved.
Created: 11/09/2008
Modified: 11/09/2008
Estimated Permutations: 151200

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