The cauda equina is the bundle of nerve roots at the end of the spinal cord that controls the feeling in the groin area and the legs; most of the muscles in the legs; and the functioning of the bladder, intestines, and genitals.

Cauda equina syndrome is a serious condition in which this bundle of nerve roots is squeezed. Cauda equina syndrome may be associated with bowel and bladder problems as well as tingling or a loss of sensation and feeling to the lower pelvic (perineal) area and the legs; these symptoms require immediate medical attention and probable surgery.

Cauda equina syndrome is caused by anything that takes too much space in the spinal canal and puts pressure on the bundle of nerves. This can include a herniated disc, infection, blood, tumour, or bone.