Ethmoid Bone

Description

Centered at the anterior cranial base, the ethmoid bone sits between the paired orbits and the superior nasal cavity, interposed anterior to the body of the sphenoid and posterior to the nasal bones and frontal bone. From an inferior view into the cranial cavity floor, the cribriform plate spans transversely, with the perpendicular plate descending in the midline toward the nasal septum and the labyrinths positioned laterally as the bony medial orbital walls. The crista galli projects superiorly from the midline, just anterior to the sphenoidal planum. Midline anatomy, made unforgiving. Clinical teaching often hinges on this region because the cribriform plate is a thin barrier separating the olfactory bulbs and meninges superiorly from the nasal cavity inferiorly, so even modest anterior skull base trauma can produce CSF rhinorrhea and anosmia. Endoscopic sinus and skull base procedures also navigate adjacent ethmoidal air cells and the lamina papyracea, where a small breach can lead to orbital emphysema or medial rectus injury. For radiology correlation, this perspective complements CT evaluation of anterior cranial fossa fractures and the relationship of the ethmoid roof to the sphenoid and frontal sinus drainage pathways. Use this illustration in gross anatomy and neuroanatomy courses when orienting learners to the internal cranial base, and in ENT or neurosurgical publications discussing anterior skull base approaches, cribriform plate defects, or olfactory pathway injuries. It also supports patient-facing education on post-traumatic CSF leak workup and repair planning. Anatomical accuracy verified by SciePro's Medical Advisory Board.