CAUDA EQUINA - The cauda equina represents a bundle of spinal nerve roots arising from the lumbar enlargement of the spinal cord and conus medullaris (the end of the spinal cord). The cauda equina runs through the lower part of the subarachnoid space within the vertebral canal below the first lumbar vertebra. It comprises the roots of all the spinal nerves below the first lumbar vertebra and provides enervation to the bladder, rectum, perineum, and lower extremities.