Insertion of the levator aponeurosis and Müller's muscle on the tarsus: a cadaveric study in caucasians

PURPOSE: To elucidate the insertion of the levator aponeurosis and Müller's muscle on the upper eyelid of Caucasians through cadaveric study. METHODS: Sagittal full thickness sections of 11 cadaveric upper eyelids in Caucasian (7 right and 4 left; age range, 78-101 years old at death; age average, 87.7 years old) were prepared and stained with Masson's trichrome. The specimens were examined microscopically to discern the configuration of the levator aponeurosis, Müller's muscle and tarsus. Main outcome measures were the position of insertion of the levator aponeurosis and Müller's muscle onto tarsus. RESULTS: In all 11 specimens, the levator aponeurosis inserted onto the distal tarsal plate, reaching the level of the marginal arterial arcade. The extension of Müller's muscle in 4/11 specimens (36.4%) surpassed the superior margin of the tarsal plates, but did not reach any further down the tarsus than its upper third; in the remaining seven specimens (63.6%), Müller's muscle attached to the superior aspect of the tarsal plate. CONCLUSIONS: This study from Caucasian cadavers suggests that fibres from the levator apponeurosis extends down to the distal portion of upper eyelid tarsus, with majority of Müller's muscle insertion being onto the superior aspect of the tarsal plate.