Spinal dura mater硬脊膜 Characters above. attached to circumference of foramen magnum Below becomes thinner at level of s2 invests filum terminale to attach at back OI COCCSpinal dura mater 硬脊膜 Characters ◼ Above, attached to circumference of foramen magnum ◼ Below, becomes thinner at level of S2, invests filum terminale to attach at back of coccyx