Morphological characterization of the posterior ethmoidal and additional ethmoidal canal in adult Croatian population

The anterior and posterior ethmoidal foramina that open into canals entering the cranial cavity are situated on the medial orbital wall. Since there may be a variable number of accessory ethmoidal foramina and their anatomy appears to be dependent on studied population, we are presenting a study of frequency and morphological characteristics of posterior and additional ethmoidal canals in adult Croatian population. In this study 439 skulls from the Zagreb skull collection were examined in order to confirm the existence of the posterior ethmoidal canal that opens in the anterior cranial fossa and the additional ethmoidal canal that opens in ethmoidal cells. Length and width of both canals were analyzed on computerized tomography scans using Analyze 8.1. software. The posterior ethmoidal canal was found in 86% of skulls. In 10% of skulls the posterior and the additional ethmoidal canals were found. In 4% of skulls we found only the additional ethmoidal canal. On skulls that had the additional ethmoidal canal the posterior ethmoidal canal was shorter and narrower. Variations in communications between orbital cavity and anterior cranial fossa, as well as ethmoidal and sphenoid sinuses could be related to increased need for vascular and nerve supply. Moreover, knowing anatomical variations of the posterior ethmoidal canal is crucial for development of safe surgical and therapeutic guidelines both in orbital and cranial regions. Based on observed communications, we suggest the revision of commonly used nomenclature for the anterior and posterior, as well as additional ethmoidal canals