A New Anatomy Finding of Levator Aponeurosis and Müller Muscle at Pretarsal Plate in Asian Males

Purpose To examine the fine anatomic structures between levator aponeurosis and Muller muscle in front of the tarsus. Materials and methods Postmortem specimens of 6 Chinese males (5 elderly men, aging from 68 to 86 years; 1 child, 10 years old) were used. A 3-μm thickness sagittal section of the central part of the upper eyelid was prepared, and the samples were examined microscopically by using hematoxylin-eosin, Masson trichrome, and anti-smooth muscle actin antibodies staining. Results There are 2 new findings in this study, one is the posterior layer of the levator aponeurosis and the other is the extensions of Muller muscle. The posterior levator aponeurosis had different insertion patterns that approximately paralleled the extension line of the levator aponeurosis at the confluence of attachment site of the orbital septum on the levator superioris. Below the confluence, it took the form of a layered insertion, and then extended to the orbicularis oculi muscle and subcutaneous tissue rather than inserting directly into tarsus. The Muller muscle was a multilayered structure at the upper border of tarsus. The superior Muller muscle extended above the peripheral arcade, and the inferior Muller muscle tendon was attached to the surface of tarsus with an Umbrella-shaped fiber. Conclusions The authors discovered that the levator aponeurosis had different insertion patterns of the posterior layers. The Muller muscle gave branches at the peripheral arcade: the anterior one crossed the peripheral arcade and extended to the tarsus, and the posterior one attached and extended to the tarsus.