Transverse ultrasonogram of the vertebral canal. Transverse ultrasonogram of the vertebral canal in a 5.7-year-old Swiss Braunvieh cow at the level of the atlanto-occipital space immediately after euthanasia. a Distance between skin and arachnoidea, b Dorsal compartment of the subarachnoid space, c Spinal cord, d Ventral compartment of the subarachnoid space, 1 Atlanto-occipital membrane, 2 Venous sinus within the epidural space, 3 Dura mater and arachnoidea, 4 Central canal, 5 Denticulate ligament, 6 Skin, 7 Nuchal ligament, 8 Major rectus capitis muscle, 9 Minor rectus capitis muscle