Bony landmarks of the medial orbital wall: An anatomical study of ethmoidal foramina

Abstract

The study determines the distribution patterns of ethmoidal foramina (EF) evaluate how they are affected by gender or bilateral asymmetry, and highlights the surgical implications on the anatomical landmarks of the orbit. Two hundred and forty-nine dry orbits were assessed. The number and pattern of EF were determined and distances between the anterior lacrimal crest (ALC), anterior (AEF) middle (MEF), posterior (PEF) ethmoidal foramina and between PEF and the optic canal (OC) were measured. The patterns of EF were classified as type I (single foramen) in 4 orbits (1.6%), type II (double foramina) in 152 (61%), type III (triple foramina) in 71 (28.5%), and type IV (multiple foramina) in 22 orbits (16.4%). Two orbits were found with five EF and a single orbit with six EF. A significant gender difference was observed for ALC-AEF distance (P ≤ 0.03), in males 23.53 ± 2.86 (20.67-26.39) versus females 22.51 ± 3.72 (18.79-26.23) mm. Bilateral asymmetry was observed for ALC-AEF distance (P ≤ 0.01). The distances ALC-AEF and ALC-PEF varied significantly according to EF classification (P ≤ 0.03 and P ≤ 0.02). The navigation ratio from ALC-AEF, AEF-PEF, and PEF-OC, in Greek population was "23-10-4 mm". A variation in the number of EF was found, ranging from 1 to 6, with the first report of sextuple EF. Although measures were generally consistent across genders and side, there are significant differences across ethnicities. These findings suggest that surgeons must consider population differences in determining the anatomical landmarks and navigation points of the orbit.

The orbit: A re‐appraisal of the surgical landmarks of the medial and lateral walls

“…The AEF and PEF are usually located on the FES (Kirchner et al, ; Standring, ; Piagkou et al, ), but can also be located superiorly (on the frontal bone) or inferiorly (on the ethmoid bone) to the FES. Depending on their location on the ethmoid bone or frontal bone, this may increase the risk of injury to underlying structures such as the ethmoidal cells (Kazak et al, ) or CSF leakage (Takahashi et al, ; Takahashi et al, ).…”

“…In trauma for example, the incidence of isolated medial orbital wall fractures occur as frequently as 55% (Choi and Flores, ), and zygomaticomaxillary complex fractures of the lateral orbital wall occur in 10% of the human population (Lee et al, ). Depending on the type of injury, reconstructive surgeries of the orbit may include optic nerve (ON) decompression, reconstruction of the skull base, fracture repair, tumor resection and endoscopic sinus surgeries (Han et al, ; Mutalik et al, ; Piagkou et al, ). To avoid complications and damage, it is essential for surgeons to have an adequate and precise knowledge of the orbital foramina and their important neurovascular structures.…”

“…There are variations in the location of the EF; although the AEF and PEF are normally assumed to be located on the frontoethmoidal suture (FES) (Kirchner et al, ; Standring, ), their location has been reported to vary superiorly or inferiorly to the FES (McQueen et al, ; Abed et al, ; Takahashi et al, ). Despite attempts to morphologically locate the foramina in ethnically diverse samples (Kirchner et al, ; Rontal et al, ; McQueen et al, ; Hwang and Baik, ; Karakaş et al, ; Akdemir et al, ; Huanmanop et al, ; Cheng et al, ; McDonald et al, ; Abed et al, ; Mutalik et al, ; Celik et al, ; Gosavi et al, ; Piagkou et al, ; Mehta and Perry, ), there is little agreement on the exact morphometric location of the AEF and PEF in the orbit.…”

“…This foramen is located in close proximity to the superior orbital fissure (SOF). Thus failure to locate the COF and to establish a safe operating field in procedures such as reconstruction of the skull base, orbital wall surgery, fracture repair, tumor resection (Piagkou et al, ) and endoscopic sinus surgeries (Han et al, ; Mutalik et al, ) may result in neurovascular injuries such as hemorrhaging in the anterior cranial fossa (Kwiatkowski et al, ; Hayashi et al, ; Abed et al, ; Celik et al, ).…”

Anatomy of the Lacrimal System

“…1.3 ) [ 19 ]. Piagkou et al found high anatomic variation, however, with anywhere from 1 to 6 ethmoidal foramina present in 249 human orbit specimens, with 61 % having 2 foramina [ 20 ].…”