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Medial canthal ligament

The medial canthal ligament is a key fibrous structure in the medial aspect of the orbit, anchoring the eyelids to the medial orbital rim and supporting the position and function of the eyelids and lacrimal apparatus. It plays a critical role in eyelid mechanics and the proper drainage of tears, and is highly relevant in both ophthalmology and radiology for trauma assessment, reconstructive surgery, and tumor evaluation.

Synonyms

  • Medial palpebral ligament

  • Medial canthal tendon

  • Internal canthal ligament

Function

  • Anchors the medial ends of the upper and lower eyelids to the anterior lacrimal crest of the maxilla and the posterior lacrimal crest of the lacrimal bone.

  • Maintains eyelid position, supporting the canthus and enabling normal blinking and closure.

  • Supports the lacrimal sac, assisting in the proper drainage of tears into the nasolacrimal duct.

  • Provides structural stability to the medial canthal region, important for both function and facial aesthetics.

MRI Appearance

  • T1-weighted images:

    • The medial canthal ligament appears as a low signal intensity linear structure at the medial canthus, best seen in thin-section, high-resolution orbital images.

  • T2-weighted images:

    • The ligament remains low signal intensity (dark) on T2 images, contrasting with adjacent orbital fat (bright) and the lacrimal sac (fluid signal, hyperintense).

  • STIR (Short Tau Inversion Recovery):

    • The ligament is hypointense (dark), similar to other dense collagenous structures; STIR sequence suppresses fat, further improving contrast with surrounding tissues.

CT Appearance

  • The medial canthal ligament is not directly visualized on standard CT scans due to its small size and fibrous density, but can be inferred as a thin, dense band along the medial canthus.

  • High-resolution, thin-section CT may show the ligament as a subtle soft tissue density extending from the medial aspect of the eyelids to the anterior lacrimal crest.

MRI images

Medial canthal ligament MRI image