filum durae matris spinalis filum du·rae ma·tris spi·na·lis (d&oobreve;r'ē mā'trĭs spī-nā'lĭs, dy&oobreve;r'ē)
n.
The termination of the spinal dura mater, surrounding the terminal filum of the cord and attached to the deep dorsal sacrococcygeal ligament.