Anat Cell Biol.  2022 Dec;55(4):497-500. 10.5115/acb.22.108.

Variant muscle fibers connecting the orbicularis oculi to the orbicularis oris: case report

• Kitagawa N
• Iwanaga J
• Tubbs R
• Kim H
• Moon YS
• Hur MS

• KMID: 2537469
• DOI: http://doi.org/10.5115/acb.22.108

Abstract

The orbicularis oculi (OOc) is a sphincteric muscle of the eyelids, whereas contraction of the orbicularis oris (OOr), another sphincteric muscle, causes narrowing of the lips. Facial muscle fibers normally blend with adjacent muscles. However, muscle fibers connecting the various facial muscles that have different actions and that are located at distant sites, such as the OOc and the OOr have been rarely reported. Herein, we report a rare case of connecting fibers between the inferior margin of the OOc and the OOr. These connecting fibers were blended with the OOr between the inserting fibers of the levator labii superioris and levator anguli oris. Contraction of such variant muscles might affect typical facial expressions.

Keyword

Orbicularis oculi; Orbicularis oris; Connecting fibers; Anatomical variations; Cadaver

Figure

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  Fig. 1 Connecting fibers between the inferior margin of the OOc and OOr. (A) At the middle of the inferior margin of the OOc, the connecting fibers (arrowheads) descended perpendicularly and passed beneath the site between the middle and the lower thirds of the nasolabial fold. Adjacent to the connecting fibers, there were several fibers (arrows) from the OOc attaching along the nasolabial fold. Skin just lateral to the nasolabial fold was removed and the remaining skin was reflected to reveal the courses and attachments of the connecting fibers and the adjacent extending fibers from the OOc. (B) The connecting fibers (arrowheads) blended with the OOr between the inserting fibers of the LLS and LAO. The several fibers (arrows) from the OOc were toward the LLSAN, LLS, and Zmi. The remaining skin was removed to expose the entire muscles in the face. (C) The extending fibers of the OOc that divided the connecting fibers (arrowheads) were attached to the maxilla just above the origin site of the LLS. The inferior margin of the OOc were reflected superiorly to reveal the course and attachment of the connecting fibers. AV, angular vein; LAO, levator anguli oris; LLS, levator labii superioris; LLSAN, lavetor labii superioris alaeque nasi; OOc, orbicularis oculi; OOr, orbicularis oris; Zmi, zygomaticus minor; Zmj, zygomaticus major.

Reference

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