Macroscopic and Endoscopic Anatomy of the Anterior Skull Base and Adjacent Structures

The anterior skull base can be divided into three segments: a midline and two symmetrically placed segments located laterally. The midline segment is the roof of the nasal cavity and serves as a watershed between the sinonasal tract and the intracranial space, whereas the lateral segments separate the intracranial compartment from the orbital content. Several peculiar anatomical areas make up the midline segment (posterior frontal plate, cribriform plate, ethmoidal roof, planum sphenoidale, and tuberculum sellae), while the lateral segments are more regular, formed by flat laminae (orbital plates of the frontal bones and lesser wings of the sphenoid). Here we detail each segment of the anterior skull base, emphasizing major landmarks, providing classifications and measurements of key areas, and cautioning the endoscopist about areas to avoid or minimize the occurrence of cerebrospinal fluid leaks, as well as providing recommendations and tips. Several endoscopic and sectional macroscopic anatomical images provide the reader with an informative, illustrative, and broad perspective of anterior skull base anatomy.