Abducens nucleus
The abducens nucleus is the originating nucleus from which the abducens nerve 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 both eyes conjugately away from the side of 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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Primary terminal nuclei of the afferent (sensory) cranial 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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