Clinical Neurology · Neuro-Ophthalmology
Ocular Motility
Localization of Ocular Motility Abnormalities
Patterns of ocular motor dysfunction and the brainstem, nerve, or cavernous/orbital location they localize to.
| Motility Disturbance | Localization/Etiology |
|---|---|
| Weber syndrome (third-nerve palsy and hemiparesis) | Anterior midbrain |
| Benedikt syndrome (third-nerve palsy and contralateral tremor) | Red nucleus and third-nerve fascicle |
| Isolated pupil-involving third-nerve palsy | Posterior communicating artery aneurysm |
| Pupil-sparing third-nerve palsy | Microvascular ischemia of the third nerve |
| Isolated fourth-nerve palsy | Dorsal midbrain/anterior medullary velum, microvascular ischemia |
| Isolated sixth-nerve palsy | Pons or sixth-nerve fascicle, demyelination/microvascular ischemia |
| Gaze palsy and facial weakness | Dorsal pons/facial colliculus |
| Third-, fourth-, and sixth-nerve palsies | Cavernous sinus |
| Third-, fourth-, sixth-nerve palsies, and optic neuropathy | Orbital apex |
| Internuclear ophthalmoplegia | Medial longitudinal fasciculus |
| Gaze palsy | Dorsal pons |
| Parinaud syndrome (upgaze palsy, eyelid retraction) | Dorsal midbrain |
Quick Facts
- Oculomotor complex is located in the dorsal midbrain, anterior to the cerebral aqueduct.
- The central caudal nucleus innervates both levator muscles.
- The superior rectus receives information from the contralateral superior rectus subnuclei, but the rest of the innervation of the third nerve is ipsilateral.
- As the oculomotor nerve enters the orbit, it separates into the superior and inferior divisions. The superior division innervates the levator palpebrae and superior rectus, whereas the inferior division innervates the pupillary sphincter, medial and inferior recti, and the inferior oblique.
- A lesion of the third nerve nucleus is exceedingly rare but will result in an ipsilateral third nerve palsy with contralateral superior rectus weakness and bilateral partial ptosis.
- Trochlear nerve floats freely in the cavernous sinus lateral to the internal carotid artery, as opposed to the third and fourth nerves, which are in the lateral wall of the sinus.
Ahmed Koriesh, MD