There are many causes of back pain, including blood vessels, internal organs, infections, mechanical, and autoimmune causes.[8] The spinal cord, nerve roots, vertebral column, and muscles around the spine can all be sources of back pain.[8] The anterior ligaments of the intervertebral disc are extremely sensitive, and even the slightest injury can cause significant pain.[9] In osteoporosis, the bones become weaker and can develop small cracks, or fractures, in the bones, resulting in pain.[10] Arthritis in the joints of the back can also result in discomfort.[10] The synovial joints of the spine (e.g. zygapophysial joints/facet joints) have been identified as the primary source of the pain in approximately one third of people with chronic low back pain, and in most people with neck pain following whiplash.[11]