Organ
Abducens nucleus
Couples the two eyes during horizontal gaze
High-yield
Damage to the nerve mainly impairs one eye’s abduction. A nuclear lesion interrupts the linked movement of both eyes toward the affected side.
Overview
The abducens nucleus coordinates looking toward its own side. Motor neurons activate that eye’s lateral rectus, while interneurons cross the midline and ascend in the opposite medial longitudinal fasciculus to recruit the other eye’s medial rectus.
Reference facts
- Location
- Dorsal caudal pons, near the floor of the fourth ventricle and immediately lateral to the medial longitudinal fasciculus
- Parts
- Lateral-rectus motor neurons and interneurons linking to the opposite oculomotor nucleus; smaller populations have other projections
- Relations
- The internal genu of CN VII loops around the nucleus beneath the facial colliculus
- Function
- Coordinates ipsilateral eye abduction with contralateral eye adduction for conjugate horizontal gaze
Clinical correlation
Damage involving the nucleus and the ipsilateral medial longitudinal fasciculus produces one-and-a-half syndrome. Injury to nearby facial nerve fibers can add ipsilateral facial weakness; this expanded combination is called eight-and-a-half syndrome.
Frequently asked questions
Where is the abducens nucleus located?
The abducens nucleus lies dorsal caudal pons, near the floor of the fourth ventricle and immediately lateral to the medial longitudinal fasciculus.
What does the abducens nucleus do?
Coordinates ipsilateral eye abduction with contralateral eye adduction for conjugate horizontal gaze.
What are the parts of the abducens nucleus?
Lateral-rectus motor neurons and interneurons linking to the opposite oculomotor nucleus; smaller populations have other projections.