The Study of Anatomic Relationship Between the Müller Muscle and the Tarsus in Asian Upper Eyelid

Abstract

This study was performed to clarify the detailed anatomic relationship between the insertion of Müller muscle and the tarsus in Asian upper eyelids. Eight upper eyelids of 4 formalin-fixed Asian cadavers (4 males; age range, 48-69 years; mean age, 60.2 years) were examined. Three perpendicular dissected sections with a 2-mm thickness were obtained from each eyelid. One section was obtained from the midline, and another 2 sections were obtained, each 3-mm from the lateral and medial ends of the tarsus, respectively. Samples were stained with hematoxylin-eosin, Masson trichrome, and antismooth muscle actin antibody and examined microscopically. Müller muscle did not insert directly in the tarsus. However, its muscle tissues were tapered to the superior margin of the tarsus, and the space between the Müller muscle and the tarsus was bridged by fibrous connective tissue strands. Meanwhile, according to a result that measured distance between the Müller muscle insertion and the tarsus, the insertion of Müller muscle was positioned closer in the tarsus at the midline section than at the lateral or medial sections. This study suggests that the Müller muscle is broadly distributed around the superior border of the tarsus as tapered, aggregated smooth muscle bundles without direct insertion on the superior border of the tarsus, despite a few limitation.