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Preseptal part of orbicularis oculi muscle

The preseptal part of the orbicularis oculi is the segment of the orbicularis oculi muscle located anterior to the orbital septum. It primarily contributes to eyelid closure, especially during blinking, and helps drain the lacrimal sac. Precise knowledge of its anatomy, function, and imaging appearance is crucial for radiologists, ophthalmologists, and oculoplastic surgeons, particularly when evaluating eyelid tumors, inflammation, or trauma.

Synonyms

  • Preseptal orbicularis muscle

  • Eyelid preseptal orbicularis

  • Anterior segment of orbicularis oculi

Function

  • Facilitates eyelid closure and blinking

  • Assists in lacrimal pump function for tear drainage

  • Protects the anterior surface of the eye

  • Contributes to facial expression

MRI Appearance

T1-weighted images:

  • Appears as a thin, linear intermediate-signal muscle band along the anterior eyelid.

  • Surrounded by hyperintense orbital and periorbital fat, providing natural contrast.

  • Pathology such as inflammation or tumor may appear hypointense relative to surrounding fat.

T2-weighted images:

  • Muscle is intermediate signal, while edema or inflammation appears hyperintense, making subtle pathology visible.

  • Fat remains bright, helping delineate the muscle borders.

STIR (Short Tau Inversion Recovery):

  • Fat suppression removes signal from surrounding fat, highlighting edema or inflammatory changes.

  • Normal preseptal muscle remains low-to-intermediate signal, while pathology appears bright hyperintense.

CT Appearance

  • Appears as a thin soft tissue density structure along the anterior eyelid.

  • Surrounding orbital fat is hypodense (dark), contrasting with the muscle.

  • Pathological changes, such as tumors, hematomas, or inflammation, appear as focal soft tissue density within the normal preseptal plane.

MRI images

Preseptal part of orbicularis oculi muscle mri axial image -img-00000-00000

MRI images

Preseptal part of orbicularis oculi muscle mri axial image -img-00000-00000_00001