Corpus: Filum terminale

The filum terminale is a narrow cord of connective tissue about 20 cm long that extends caudally from the conus medullaris of the spinal cord.

The filum terminale consists of two sections:

• The upper section (filum terminale internum) is approx. 15 cm long and extends approximately to the level of the 2nd sacral vertebra. It lies as an extension of the pia mater spinalis within the dural sac and is surrounded by the nerve cords of the cauda equina. It is distinguished from them by its bluish colour.
• The lower section is known as the filum terminale externum. Here the tissue fuses with the dura mater spinalis and forms a coarse cord that finally attaches to the first coccygeal vertebra. This part is sometimes also referred to as the "coccygeal ligament".