Levator Palpebrae Superioris: Development, Structure, Variation, and Clinical Implications

Abstract

The purpose of this review is to present a comprehensive synopsis of the current literature on the development and structure of the levator palpebrae superioris muscle (LPS) with an emphasis on known variations as well as clinical implications of said structures. Furthering an understanding of LPS variations and clinical presentations will afford a more informed approach for surgical reconstruction procedures as well as guide clinical considerations during presentations of lid lag, blepharoptosis, eyelid retractions, etc., that are prevalent with congenital ptosis, age‐related ptosis, and Grave’s disease. Embryologically, the LPS arises from the superior rectus around the 46th day of the prenatal period and remains bound and share a common epimysium that begins dividing by the fifth fetal month. Subsequent anterograde projection of the LPS allows for connections with the skin through the ciliary portion of the orbicularis oculi muscle. Anatomic variations of the LPS have been noted at higher incidences in fetal studies when compared to adult cadaveric dissections. Variations arising from muscular slips which split off the medial or lateral margins have been described unilaterally or bilaterally and can progress to acquire their own muscular identity and can be supplied by branches of the trochlear n.