The frontal recess and anterior ethmoid sinus continue to challenge otolaryngologists performing sinus surgery. Anatomic descriptions based on radiographic analysis rather than anatomic dissection can oversimplify the regional anatomy and lead to intraoperative uncertainty and an overreliance on image guided surgical technology. Recognizing subtle yet consistent anatomic features can help orient endoscopic sinus surgery, facilitate precise dissection, and reduce surgical challenges. Recently, nuanced attributes of ethmoid sinus anatomy, referred to herein as “microanatomic” features, have been reported that can assist in surgical orientation. These include superior extensions of the uncinate process, the anterior ethmoid genu, the ponticulus ethmoidalis, and the small uncinate and bullar attachments to the middle turbinate that delineate the entrances to the frontal, suprabullar and retrobullar recesses. Additionally, embryologic determinants provide insight in anatomic areas that express variation, such as the ethmoid labyrinth. Unfortunately, instruction in sinus embryology for otolaryngology trainees is often limited. This presentation will introduce consistent, newly appreciated features of ethmoid anatomy, highlight their endoscopic appearance and review their association to foundational sinonasal anatomy in a way that can further an anatomic landmark based surgical approach for the attendee. Embryologic specimens, endoscopic surgical dissections, gross anatomic dissections, tri-planar CT images and new high-resolution 3D-CT scan technology will be used to demonstrate these practical anatomic hallmarks. Based on the presenter’s extensive experience studying and researching sinus anatomy over several decades and personal analysis of several U.S. embryology collections, the presentation is designed to provide a foundation for otolaryngologists-in-training as well as helpful anatomic insights to practicing otolaryngologists. As the anterior ethmoid and frontal recess are the most challenging areas in surgery, they will be stressed.