Figure 6.

Extraocular muscle origins and their anomalous connections: a revision of our previous diagram (IOVS 2019; 60:4573). Anterior view of the right orbital apex. The SR originates from the lateral half of the optic canal opening, and the LR, IR, and MR muscles provide a common tendon originating from the medial wall of the orbital fissure. The MR has an accessory head (MRacc) that originates from the superomedial margin of the optic canal opening. In contrast to our previous diagram, the MRacc passes along the lateral side of the origin of the SO. Thin tendons likely connect the SR and the LR and/or IR (arrowheads). The connection is usually over the abducent and oculomotor nerve (ABN, OCN), but likely passes along the inferior side of the nerve. ON, optic nerve.