The medial canthal tendon attaches to the medial bony orbit by superficial and deep components that attach to the anterior and posterior lacrimal crests (Fig 2-8 and 2-9) (2,3). The medial canthal tendon originates at the nasal border of the upper and lower tarsi, where the preseptal muscle divide into superficial and deeps heads (4). The lacrimal puncta are located here. Thus, the lacrimal canaliculi of the upper and lower lid margins extend from the medial border of the tarsi toward and behind the medial canthus. Continuing medially, the tendon fans out to insert into the anterior lacrimal crest and beyond onto the frontal process of the maxilla. The anterior lacrimal crest, which is 2 to 3 mm medial to the canthal apex, protects the lacrimal sac. Thus, an incision farther medial than 3 mm from the canthus misses both the canaliculi and the sac.
The anterior horizontal segment is the strongest component of the medial canthal tendon complex and is attached most firmly at the anterior lacrimal crest. The thinner posterior limb inserts on the posterior lacrimal crest and functions to maintain the eyelids in a posture tangent to the globe. The resultant vectors of all of the canthal attachments suggests that resuspension of the entire complex following disruptionshould be posterior and superior to the anterior lacrimal crest.
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