Abstract
Purpose :
The anatomy of the extraocular rectus muscle insertions are clinically relevant in the field of ophthalmology. This descriptive cadaveric study determines relative degree orientation of the superior, lateral, and inferior recti with respect to the medial rectus, as well as investigating the distances between the rectus muscle insertions.
Methods :
30 cadavers (50% female, mean age = 81.86 years, SD 12.16) were included for a total of 60 eyes. For each eye, a lateral canthotomy with superior and inferior cantholysis was performed followed by a peritomy. Muscle hooks were then used to access and isolate the recti muscles. The degree orientation was determined by marking the muscle midpoints at insertion, using the center of the cornea as the vertex, and measuring the angle with the Angle Meter app (Fig. 1). The distances between recti were measured from the same muscle midpoints at insertion using calipers.
Results :
The degree orientations with respect to the medial rectus are displayed in Figure 2, and were as follows: superior rectus (mean = 93.14, SD = 3.04, min. 82.3, max. 100.3), lateral rectus (mean = 180.21, SD = 5.65, min. 170.5, max. 190.6), and inferior rectus (mean = 90.57, SD = 4.47, min. 84.0, max. 98.9). The distances (measured in mm) between recti muscle midpoints at insertion included medial rectus to inferior rectus (mean = 13.64, SD = 0.54), inferior rectus to lateral rectus (mean = 13.79, SD = 0.75), lateral rectus to superior rectus (mean =13.54, SD = 0.63), and superior rectus to medial rectus (mean = 13.83, SD = 0.75).
Conclusions :
This is a novel study of the extraocular muscle degree orientation performed with an innovative measuring approach. We found the recti degree orientation to approximate right angles between each muscle, however, there was wide variability. The mean distance between rectus muscle insertions were nearly uniform.The degree orientation of the insertions relative to the medial rectus have not been previously reported and may have surgical application in the field of ophthalmology.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.