“…While some individual variation exists with regard to the precise location of the anterior ethmoidal structures, numerous studies have described multiple anatomical landmarks to aid in the intraoperative identification of the foramen, canal, and artery. 10,20,28,31 A literature review of anatomical references that can be used to help identify the anterior ethmoidal artery and canal is presented in Table 1, with distances measured from the anterior crest of the nasolacrimal fossa, anterior axilla of the middle turbinate, anterior nasal spine, and the anterior face of the ethmoidal bulla. Similarly, the PEA can be identified based on the distance from the nasion, the optic foramen, or the anterior ethmoidal foramen as shown in Table 2.…”