Anatomy of the Corrugator Muscle.

The aim of this article is to systematically review the anatomy and action of the corrugator muscle. PubMed and Scopus were searched using the terms "corrugator" AND "anatomy." Among the 60 full texts from the 145 relevant abstracts, 34 articles without sufficient content were excluded and 4 articles drawn from the reference lists were added. Among the 30 articles analyzed (721 hemifaces), 28% classified by oblique head and transverse head, and 72% did not. Corrugator originated mostly from the medial supraorbital rim (45%), followed by the medial frontal bone (31%), the medial infraorbital rim (17%), and the upper nasal process (7%). Corrugator extended through the frontalis and orbicularis oculi (41%), only the frontalis (41%), or only the orbicularis oculi (18%). Corrugator ran superolaterally (59%), or laterally (41%). Corrugators inserted mostly to the middle of the eyebrow (57%), or the medial half of the eyebrow (36%), but also to the glabella region (7%). The length of the corrugator ranged 38 to 53 mm. The transverse head (23.38 mm) was longer than the oblique head (19.75 mm). Corrugator was thicker at the medial canthus than at the midpupillary line. Corrugator was innervated by the temporal branch of the facial nerve (66%), the zygomatic branch (17%), or the angular nerve (zygomatic branch and buccal branch, 17%). Supraorbital nerve (60%) or supratrochlear nerve (40%) penetrated the corrugator. The action was depressing, pulling the eyebrow medially (91%), or with medial eyebrow elevation and lateral eyebrow depression (9%). Surgeons must keep this anatomy in mind during surgical procedures.