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CN VI: Abducens nerve - Coggle Diagram
CN VI: Abducens nerve
Anatomy
- Has only a somatic motor component
- Function = Move the eye laterally
- Enters the cavernous sinus
- Enters the orbit at the superior orbital fissure
- Lateral rectus muscle
Abducens nucleus located in the lower pons:
- Lower motor neurons
- Internuclear neurons = Axons ascend via MLF -> Medial rectus LMN in contralateral oculomotor nucleus at the level of superior colliculus => Coordination of the lateral gaze
Damage
Brainstem
Infarction, tumor, or demyelination
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Cavernous sinus
Disease process within the sinus:
- Carotid aneurysm
- Sinus thrombosis
- Infection
- Inflammation
- Tumor
Other CN are affected at this site = III, IV, V1, V2
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Disorders
A peripheral or central lesion involving the abducens nucleus produces paralysis of the lateral rectus muscle
- Medial strabismus (inability for both eyes to be focused on the same object)
- Affected eye cannot abduct
- Affected eye will tend to lay medially when looking forward
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Test
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- Affected eye cannot move beyond the midline of the visual field
- Patient unable to identify the object located in the lateral aspect