The anatomy of the lateral canthal tendon.

This report documents the anatomy of the lateral canthus using gross dissection, histologic examination, computed tomography, magnetic resonance imaging, and clinical measurement. Lateral canthal dissections of 16 cadaver orbits demonstrated a well-defined attachment of the tarsal plates to the orbital rim, averaging 10.6 mm in length and 10.2 mm in width at their insertion on Whitnall's tubercle, 1.5 mm behind the orbital rim and 9.7 mm inferior to the frontozygomatic suture. Histologic examination showed a band of dense fibrous tissue attached to the tarsal plates, with intermingled muscle fibers from the pretarsal orbicularis oculi muscle. A small pocket of fat was identified posterior to the orbital septum and anterior to the lateral canthal tendon. Clinical measurements of normal adults revealed 2 mm of lateral movement of the canthal angle during abduction, apparently caused by posterior fibrous attachments to the check ligament of the lateral rectus muscle.