High-Resolution 3-Dimensional MRI of the Oculomotor Nerve: Anatomic and Pathologic Considerations by Segment

Background: CN III is a pure motor cranial nerve that innervates the majority of the extraocular muscles. CN III palsy is the most common cranial nerve palsy with an incidence of 3–4 cases per 100,000. Evidence Acquisition: High-resolution, 3-dimensional, skull base MRI allows for high spatial resolution and high signal-to-noise ratio allowing for optimal evaluation of CN III pathology by segment. Results: A systemic approach is used to describe the segmental anatomy of CN III, its vascular supply, clinical pathologic manifestations, and imaging correlate. Conclusions: We present a segmental approach to high-resolution 3-dimensional MRI of the oculomotor nerve from nuclear to extraforaminal segments.