Abducens nucleus

Brain: Abducens nucleus
The cranial nerve nuclei schematically represented; dorsal view. Motor nuclei in red; sensory in blue. The olfactory and optic centers are not represented. (Abducens nucleus is VI)
Latin	nucleus nervi abducentis
Gray's	subject #187 787
Part of	Pons
Artery	Pontine branches of the Basilar artery
NeuroNames	hier-580
NeuroLex ID	birnlex_1366

The abducens nucleus is the originating nucleus from which the abducens nerve (VI) emerges - a cranial nerve nucleus. This nucleus is located beneath the fourth ventricle in the caudal portion of the pons, medial to the sulcus limitans.

The abducens nucleus along with the internal genu of the facial nerve make up the facial colliculus, a hump at the caudal end of the medial eminence on the dorsal aspect of the pons.

Clinical significance

Damage to the abducens nucleus causes monocular medial ophthalmoparesis: specifically, loss of the ability to move the ipsilateral eye outward (abduction). This is also seen in damage of the abducens nerve.

In contrast, damage to the area of the nucleus can also result in lateral gaze paralysis: loss of the ability to move either eye in the direction of the side with the lesion. This is due to damage to both the motoneurons and interneurons projecting through the medial longitudinal fasciculus to the contralateral medial rectus neurons.

Additional images

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  Nuclei of origin of cranial motor nerves schematically represented; lateral view.

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  Scheme showing central connections of the optic nerves and optic tracts.

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  Figure showing the mode of innervation of the Recti medialis and lateralis of the eye.

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  Axial section of the Brainstem (Pons) at the level of the Facial Colliculus

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  Vestibulo-ocular reflex

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  Brain stem sagittal section

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  Section through lower pons. Abducens nucleus is labeled #4.

External links

• Brainstem at UWisc 13VNAN
• MedEd at Loyola Neuro/frames/nlBSs/nl27fr.htm
• Template (look for "GSE")
• BrainMaps at UCDavis Abducens nucleus

• NIF Search - Abducens Nucleus via the Neuroscience Information Framework