Anatomy of medial canthal tendon in Caucasians

Background: To analyse the anatomy of the medial canthal tendon in Caucasians and to clarify the true anatomical nature of its posterior limb. Methods: This was an experimental anatomic study. Seven Caucasian cadavers (11 eyelids; age range: 78-101years at death). Anatomical dissection and histological examination of cadaveric eyelids fixed in 10% buffered formalin was performed. The axial sections were made in parallel with the eyelid margin at 1mm superior or inferior to the upper or lower eyelid margins, respectively. The histological specimens were first dehydrated and embedded in paraffin and then divided into 7μm thickness sections and stained with Masson's trichrome. Microscopic photographs were taken with a digital camera system attached to the microscope. Results: The posterior limb of the medial canthal tendon was not detected in any of the specimens. The medial check ligament supported the posterior aspect of Horner's muscle and inserted into the medial orbital wall through the periosteum. The lacrimal diaphragm around the posterior lacrimal crest ran almost parallel to Horner's muscle and was usually difficult to distinguish from the tendon of Horner's muscle. Conclusions: The posterior limb of the medial canthal tendon was not detected in any of the studied specimens. This anatomical structure appears to be Horner's muscle, and the lacrimal diaphragm.