Conus Medullaris

The conus medullaris ("medullary cone") is the terminal end of the spinal cord. It occurs near lumbar vertebral levels 1 (L1) and 2 (L2). After the spinal cord tapers out, the spinal nerves continue as dangling nerve roots called cauda equina. The filum terminale is a slender, threadlike prolongation of the spinal cord, which is a projection of the pia mater to form a ligament for support, from the conus medullaris to the back of the coccyx. The upper end of the conus medullaris is usually not well defined.