Structure and Function of the Abducens Nucleus
- Two primary neuron types in the abducens nucleus: motorneurons and interneurons
- Motorneurons drive contraction of the ipsilateral lateral rectus muscle via the abducens nerve, causing outward eye rotation (abduction)
- Interneurons relay signals from the abducens nucleus to the contralateral oculomotor nucleus
- Motoneurons in the oculomotor nucleus drive contraction of the ipsilateral medial rectus muscle, rotating the eye inward (adduction)
- Abducens nucleus generates coordinated movements of both eyes in the same direction
- Electrical stimulation of the abducens nucleus generates conjugate eye movements
- Lesions to the axonal tract of interneurons disrupt conjugate eye movements through paralysis of the contralateral eye
- Abducens nucleus plays a role in eye movements between distant targets
- Similar discharge patterns observed in motoneurons and interneurons during slow and fast conjugate eye movements
Clinical Significance of the Abducens Nucleus
- Infantile Esotropia Syndrome may be caused by problems in the firing rate of the abducens nucleus
- Differences in firing rates observed in monkeys with induced strabismus
- Damage to the abducens nerve causes monocular ipsilateral lateral ophthalmoparesis
- Damage to the abducens nucleus causes lateral gaze palsy
- Contralateral eye can still move in the direction of the lesion during convergence movements
Additional Images
- Nuclei of origin of cranial motor nerves schematically represented; lateral view
- Scheme showing central connections of the optic nerves and optic tracts
- Figure showing the mode of innervation of the Recti medialis and lateralis of the eye
- Axial section of the Brainstem (Pons) at the level of the Facial Colliculus
- Vestibulo-ocular reflex
- Brain stem sagittal section
- Section through lower pons. Abducens nucleus is labeled #4
References
- Sinnatamby, Chummy S. (2011). Lasts Anatomy (12thed.). p.478. ISBN978-0-7295-3752-0
- doi:10.1167/iovs.14-16177 Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc. www.iovs.org j
- ISSN1552-5783
- Walton MMG, Mustari MJ,Willoughby CL, McLoon LK. Abnormal activity of neurons in abducens nucleus of strabismic monkeys. Invest Ophthalmol Vis Sci. 2015;56:10–19
- doi:10.1167/iovs.14-15360
- Van Horn MR, Waitzman DM, Cullen KE. Vergence neurons identified in the rostral superior colliculus code smooth eye movements in 3D space. J Neurosci. 2013;33:7274–7284
External Links
- MedEd at Loyola
- Neuro/frames/nlBSs/nl27fr.htm
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 near the midline, medial to the sulcus limitans.
| 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) | |
| Details | |
| Part of | Pons |
| Artery | Pontine branches of the Basilar artery |
| Identifiers | |
| Latin | nucleus nervi abducentis |
| MeSH | D065827 |
| NeuroNames | 585 |
| NeuroLex ID | birnlex_1366 |
| TA98 | A14.1.05.411 |
| TA2 | 5941 |
| FMA | 54504 |
| Anatomical terms of neuroanatomy | |
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.
