Part 1: Primary EOM Actions & Conjugate Gaze – The Foundation
Click here to access the handout – a deeper dive into the primary extraocular muscle actions and how conjugate gaze creates the compass foundation for clinical assessment
I recently made a bold claim: You cannot holistically assess vestibular dysfunction without understanding ocular motility.
Today, we start building that foundation.
Part 1 of our 5-part series begins where all eye movement understanding must begin: How do the eyes actually move together?
The answer is conjugate gaze—both eyes moving in the same direction as a coordinated team. When your patient looks right, BOTH eyes move right. But they use different muscles to get there:
→ Right eye: Right Lateral Rectus (CN VI)
→ Left eye: Left Medial Rectus (CN III)
This pairing isn’t random. It’s the foundation of every clinical observation you’ll make—from smooth pursuits to VOR assessment to nystagmus interpretation.
Understanding conjugate gaze answers questions like:
*Why do we test eye movements in specific directions?
*How do cranial nerve lesions create predictable patterns?
*What’s actually happening when you observe “disconjugate” movement?
This is Part 1. We’re building toward understanding why posterior canal BPPV creates “upward” nystagmus when the muscles pull DOWN (Part 5). Each piece builds on the last.
By Bridgett Wallace, PT, DPT ~ 360 Neuro Health Co-Founder & Director of Clinical Education
