terminal filum

ter·mi·nal fi·lum

[TA] a long connective tissue (pia mater) strand extending from the extremity of the medullary cone to the inner aspect of the spinal dural sac (pial part of filum terminale [TA], * filum terminale internum); continuous with stout strands of connective tissue attaching the spinal dural sac to the coccyx (dural part of filum terminale [TA], * coccygeal ligament, and * filum terminale externum). Synonym(s): filum terminale [TA], nervus impar, terminal thread

ter·mi·nal fi·lum

(tĕr'mi-năl fī'lŭm) [TA] A slender strand of connective tissue extending from the conus medullaris to the coccyx; its internal or pial portion lies along the nerve fibers of the cauda equina and terminates at the distal tip of the dural sac (S2 level); its tougher external or dural portion, commonly called the coccygeal ligament, anchors the dural sac to the coccyx.