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Upper extremity muscle function and innervation 02

Topic: Anatomy

Created on Monday, August 18 2008 by jdmiles

Last modified on Monday, August 18 2008.

During a needle EMG, you notice a large number of fibrillations in the abductor pollicis brevis 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 cervical spinal cord lesion
 
        B) A lesion in the ulnar nerve
 
        C) A lesion in the lateral cord
 
        D) A lesion in the lower trunk
 
        E) A C6 radiculopathy
 

 


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This question was created on August 18, 2008 by jdmiles.
This question was last modified on August 18, 2008.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ANSWERS AND EXPLANATIONS




A) a cervical spinal cord lesion

This answer is incorrect.


The fibrillations suggest an active peripheral nerve lesion. The abductor pollicis brevis muscle receives innervation from the median nerve, the medial cord, the lower trunk, and the C8 and T1 nerve roots.  (See References)

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B) a lesion in the ulnar nerve

This answer is incorrect.


The fibrillations suggest an active peripheral nerve lesion. The abductor pollicis brevis muscle receives innervation from the median nerve, the medial cord, the lower trunk, and the C8 and T1 nerve roots.  (See References)

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C) a lesion in the lateral cord

This answer is incorrect.


The fibrillations suggest an active peripheral nerve lesion. The abductor pollicis brevis muscle receives innervation from the median nerve, the medial cord, the lower trunk, and the C8 and T1 nerve roots.  (See References)

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D) a lesion in the lower trunk

This answer is correct.


The fibrillations suggest an active peripheral nerve lesion. The abductor pollicis brevis muscle receives innervation from the median nerve, the medial cord, the lower trunk, and the C8 and T1 nerve roots.  (See References)

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E) a C6 radiculopathy

This answer is incorrect.


The fibrillations suggest an active peripheral nerve lesion. The abductor pollicis brevis muscle receives innervation from the median nerve, the medial cord, the lower trunk, and the C8 and T1 nerve roots.  (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 02
Question ID: 081808096
Question written by J. Douglas Miles, (C) 2006-2009, all rights reserved.
Created: 08/18/2008
Modified: 08/18/2008
Estimated Permutations: 198000

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