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
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.
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.