Anatomic study of the insertions of the levator aponeurosis and Müller's muscle in Oriental eyelids.

To clarify the detailed anatomy of the insertions of the levator aponeurosis and Müller's muscle, 10 upper eyelids of 5 fixed Japanese cadavers were examined. The eyelids were dissected in a manner that the authors devised to disclose the delicate pretarsal structures in close proximity. After removing the orbital roof and fat, they divided the levator aponeurosis at the origin and dissected along its posterior aspect up to the upper tarsal area. The dissected eyelids were evaluated grossly and histologically with a special staining technique. Gross and histological examinations revealed that the dense collagenous levator aponeurosis was transformed distally into fine elastic fibers, which inserted into the pretarsal orbicularis layer. They also found a distinct fascia covering the anterior aspect of the tarsus that continued proximally to Müller's muscle. Conclusively, the levator aponeurosis has no direct collagenous insertion into the tarsus, but is connected mainly to the pretarsal tissue via fine elastic fibers. A fibrous tissue covering the anterior aspect of the tarsus is not the levator aponeurosis, but an extension of Müller's muscle.