Anatomic Origin of the Preseptal Orbicularis Oculi Muscle Beneath the Medial Canthal Tendon in Caucasian Eyes

Objectives: To histologically investigate the origin of the preseptal orbicularis oculi muscle in relation to the medial canthal tendon. Methods: Histologic analysis was conducted on 8 medial canthi from 4 fresh Caucasian cadavers (age range: 62–78 y old, average 70.75 y). Medial canthal tissues were harvested and sectioned perpendicular to the medial canthal tendon, 4 mm medial to the medial commissure. The specimens were stained using Masson Trichrome for microscopic evaluation. Results: The preseptal orbicularis oculi muscles from the upper and lower eyelids were not directly continuous. Instead, tendinous tissue was identified between them, which was integrated with the anterior medial canthal tendon. Conclusion: The preseptal orbicularis oculi muscle originates from and inserts into the tendinous tissue beneath the medial canthal tendon. This tendon is structurally integrated with the anterior medial canthal tendon.