Accessory Muscles Associated With the Levator Palpebrae Superioris Muscle in 100 Cadavers

Purpose:This study aimed to determine the variations of the levator palpebrae superioris muscle and to reveal its morphological features.Methods:This study conducted on 100 adult orbit cadavers in the Department of Anatomy, Istanbul University, used an exploratory, descriptive research design. The anatomical and morphological variations of the levator palpebrae superioris muscle and its relationship with the superior ophthalmic vein were evaluated.Results:Variations of levator palpebrae superioris muscle were discovered in 11 of 100 orbits. Single (9%), double (1%), and triple (1%) accessory muscle slips were observed. The origin of accessory muscle slips showed variation as the accessory muscle slips originated either from the proximal or distal half of the levator palpebrae superioris muscle. Also, the insertions of accessory muscle slips were variable, as they were inserted into levator aponeurosis, trochlea, lacrimal gland, lateral orbital wall, or the fascia of the superior ophthalmic vein.Conclusions:Accessory muscles associated with levator aponeurosis were found in a significant proportion of cadavers. These muscles may cause confusion in orbital surgery and should be taken into account during surgical planning and orientation in the superior orbit. This study discovered variations of the levator palpebrae superioris muscle in a significant proportion of cadavers, with single, double, and triple accessory muscle slips originating from different parts and inserting in various locations.