[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). SYN: filum terminale [TA], nervus impar, terminal thread.