Anatomical Study of the Infraorbital Nerve and Surrounding Structures for the Surgery of Orbital Floor Fractures

Abstract

The infraorbital nerve (ION) can easily be damaged by orbital trauma and periorbital surgical manipulations, due to its abutment to the orbital floor. Anatomic variability of the ION and surrounding structures has infrequently been documented. The aim of this study is to give precise anatomical knowledge about the ION with surrounding structures, to avoid iatrogenic injury of the ION during periorbital procedures. Forty orbits of 40 skull subjects (20 males and 20 females) were studied to analyze structures around the ION. The authors located the ION, infraorbital canal/groove (IOC/G), and infraorbital foramen (IOF), using several reference points. The various distances were also measured between those structures, and statistically analyzed. The authors compared the left and right sides, and analyzed the differences between both sexes. The IOF was also investigated regarding the shape and presence of the accessory IOF. Three different types of orbital floor osseous anatomy were made based onmacroscopic analysis. Type 1 shows no groove, and the ION enters the canal covered by the roof (5 patients, 12.5%). Type 2 revealed a pseudocanal, which has a very thin, almost transparent roof (26 patients, 65.0%). Type 3 consists of the ION traveling in a true groove, before entering an IOC (9 patients, 22.5%). IOG/C complexes took the upward lateral course, until exiting via the IOF. The mean +/- SD length of the IOC was 12.86 +/- 3.79 mm, and of the IOG was 16.15 +/- 2.88 mm. The calculated combined mean length of the IOC/G complex was found to be 29.01 +/- 3.17 mm. An accessory IOF was found in 35% of the skulls (50% in male and 20% in female skulls), with a higher frequency on the left side in both male and female skulls. These results can increase the authors' knowledge of the anatomic variability of the infraorbital region, and help facial plastic surgeons during their surgical manipulations prevent any possible iatrogenic injury of the ION.