Comparison of the Superior and Inferior Rectus Muscles in Humans: An Anatomical Study with Notes on Morphology, Anatomical Variations, and Intramuscular Innervation Patterns

Figure 8

Schematic drawing simulating MRI or CT coronal scans that show the spatial organization of muscular structures within the orbit in the presence of atypical muscular slips that link the superior and inferior rectus muscles. The drawings were prepared on the basis of comparison of different MRI scans by Khitri and Demer (2010) and Kightlinger et al. (2017). (a) Complete muscular bridge seen between superior and inferior rectus muscles (marked by grey arrowheads). On drawing (b), only fragments of certain heads of the supernumerary rectus were captured (grey arrowheads). ir: inferior rectus muscle; lr: lateral rectus muscle; lps: levator palpebrae superioris muscle; mr: medial rectus muscle; sr: superior rectus; so: superior oblique muscle; on: optic nerve. This figure is a drawing derived from Haładaj et al. (2018) under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium.

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