Extraocular muscles
Topic: Anatomy
Created on Tuesday, July 11 2006 by
Last modified on Wednesday, December 31 1969.
A 81 year-old male spinach biologist visits you in your neighbor's kid's treehouse, complaining of diplopia.
You note that most of the time that he is facing you and talking, he sits with his chin turned toward his right shoulder and his left eye adducted.
Based on this information alone, you suspect that there may be a paresis of which extraocular muscle?
A) Right lateral rectus B) Left inferior rectus C) Left oblique rectus D) Left inferior oblique E) Left superior oblique
This question was created on July 11, 2006 by .
This question was last modified on December 31, 1969.
ANSWERS AND EXPLANATIONS
A) right lateral rectus
This answer is correct.
This presentation is typical of a paresis of the right lateral rectus. A patient with a paresis of the right lateral rectus muscle will have impaired adbuction of the right eye, and is likely to try to minimize his diplopia by looking at the world with his chin turned toward his right shoulder and his left eye adducted. (
See References)
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B) left inferior rectus
This answer is incorrect.
This presentation is typical of a paresis of the right lateral rectus. A patient with a paresis of the left inferior rectus muscle will have impaired depression and outward rotation of the left eye, and is likely to try to minimize his diplopia by looking at the world with his chin held down with no extraordinary tilting of his head. (
See References)
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C) left oblique rectus
This answer is incorrect.
This presentation is typical of a paresis of the right lateral rectus. The left oblique rectus is not a real muscle. (
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D) left inferior oblique
This answer is incorrect.
This presentation is typical of a paresis of the right lateral rectus. Paresis of the left inferior oblique muscle does not present in this way. (
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E) left superior oblique
This answer is incorrect.
This presentation is typical of a paresis of the right lateral rectus. A patient with a paresis of the left superior oblique muscle will have impaired depression and inward rotation of the left eye, and is likely to try to minimize his diplopia by looking at the world with his chin held down and his head tilted and turned with his right ear held close to his right shoulder. (
See References)
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References:
1. Ross, R.T. (1999). How to Examine the Nervous System, 3rd Edition. Appleton & Lange, Stamford, Connecticut. Pp. 45-60 | |
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anatomy
Extraocular muscles
Question ID: 0000003
Question written by . (C) FrontalCortex.com 2006-2009, all rights reserved.
Created: 07/11/2006
Modified: 12/31/1969
Estimated Permutations: 0