SEP 23, 2016
Many of our 19th-century beliefs about the extraocular muscles (EOMs) are wrong:
- EOMs are homogeneous structures that rotate the globe.
- EOMs follow straight paths from orbital apex to scleral insertion.
- Everyone has the same arrangement of EOMs.
- Abnormalities of EOMs are limited to underaction (paralysis or paresis), overaction, innervational miswiring, or stiffness.
- All important pathophysiology of EOMs can be diagnosed by clinical motility examination.
- Orbital connective tissues and EOM sleeves are not clinically very important.
Revelations from 21st-century science:
- Surface coil MRI of living human orbits has near microscopic resolution.
- Digital imaging of immuno- and histochemically stained whole human orbits permits 3D reconstruction and correlation with in vivo MRI.
- Classical physiologic data was equivocal and can be more satisfactorily reinterpreted in light of recent anatomical findings.