Extradural neural axis compartment

The lengthy, continuous, slender extradural neural axis compartment (EDNAC) , which extends from the coccyx to the orbit, has been not so much discover ed as recognized. Through this compartment run arteries, myelinated and unm yelinated nerves, and valveless veins. Adipose tissue is abundant in the or bital and spinal segments, possibly due to movement requirements, although it is very sparse in the skull base segment, the last segment to be recogni zed as a continuation of the EDNAC, which connects Breschet's veins to the orbit. The lateral sellar compartment (in older terminology, the cavernous sinus) is an enlarged segment of this EDNAC along the skull base connecting the orbit with the extradural space through the superior orbital fissure a nd down the dorsum to Breschet's veins of the basilar process of the occipi tal bone. Understanding the continuity of the EDNAC should help the student understand any segment, particularly the skull base.