(from the article `eye, human`) ...of these holes is that formed by the optic nerve, the posterior scleral foramen. The outer two-thirds of the sclera in this region continue ...
An extension of the dura mater that ensheathes the roots of spinal nerves or, more particularly, the vagina externa nervi optici. ... (05 Mar 2000) ... 
the external investment of the optic nerve.
Type: Term Definitions: 1. an extension of the dura mater that ensheathes the roots of spinal nerves or, more particularly, the vagina externa nervi optici.