Denticulate ligaments

The denticulate ligaments are bilateral triangular lateral extensions of pia mater that anchor the spinal cord to the dura mater.

They are formed by pia mater of the spinal cord coursing in-between the dorsal and ventral nerve roots bilaterally. They function to provide stability to the spinal cord within the vertebral canal . There are usually 21 pairs evenly spaced along the length of the spinal cord but their number can range from 18 to 24 pairs. The first (superiormost) pair inserts into the lateral borders of the foramen magnum, with the vertebral artery anterior to them and the hypoglossal nerve (CN XII) posterior. The inferiormost pair is at the level of the conus medullaris, namely, between the T12 and L1 segmental nerve roots, and its pia mater fuses with the filum terminale.

Each triangular ligament has a vertically oriented base that emanates from the spinal cord between the exit point of the ventral root and entry point of the dorsal root, and an apex which points laterally and attaches to the dura mater just posterosuperior to the neural foramen . They are thickest in the cervical spine.