abducens nucleus

abducens motor nuclei

Nucleus located beneath the floor of the 4th ventricle in the pontine tegmentum, containing motor neurons innervating the lateral rectus muscle of the eye (Brodal, Neurological Anatomy, 3rd ed., 1981, pg 533).

Type Muscle
Latin Name abducens motor nuclei
FMA ID 54504

Frequently Asked Questions

What is the abducens nucleus?
The abducens nucleus (abducens motor nuclei) is a cluster of motor neurons located beneath the floor of the fourth ventricle in the pontine tegmentum of the brainstem. It contains the motor neurons that directly innervate the lateral rectus muscle of the eye via the abducens nerve.
Where is the abducens nucleus located?
The abducens nucleus is situated in the dorsal pons, just beneath the floor of the fourth ventricle in the pontine tegmentum. It lies near the midline and is closely associated with the fibers of the facial nerve, which loops around it internally (forming the facial colliculus).
What is the function of the abducens nucleus?
The abducens nucleus contains two types of neurons: motor neurons that directly drive the lateral rectus muscle (causing eye abduction), and internuclear neurons whose axons cross the midline and ascend in the medial longitudinal fasciculus to coordinate horizontal gaze with the contralateral medial rectus.
What conditions can affect the abducens nucleus?
Lesions at the abducens nucleus level cause an ipsilateral gaze palsy — the inability to direct both eyes to that side — rather than just an isolated lateral rectus palsy. Multiple sclerosis, pontine glioma, and vascular brainstem disease can affect this nucleus.
How is the abducens nucleus different from the abducens nerve?
The abducens nucleus is the source of the abducens nerve fibers in the brainstem, while the abducens nerve is the peripheral nerve that exits the brainstem and travels to the eye. Damage at the nucleus level produces a full conjugate gaze palsy, whereas peripheral nerve damage only affects one eye's lateral movement.

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Educational Disclaimer

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Data sources: Terminologia Anatomica, Foundational Model of Anatomy, Wikidata.