Injury or weakness can cause the inner jelly like portion of the disk to protrude through the outer ring. This is known as a slipped or herniated disk. This causes pain and discomfort. If the slipped disk compresses one of your spinal nerves, you may also experience tingling, numbness and pain along the affected nerve. As the lumbar spine (lower back) carries most of the body weight, it tends to “slip” more than higher levels.

Human Spine is made of up 33 bones (vertebrae) that are cushioned by discs.These vertebrae are divided by region: neck (cervical spine), mid-back (thoracic spine), and low back (lumbar spine). At the lower end of your spine, you also have the sacrum and the coccyx, which is commonly called your tailbone. Discs are present between these bones. The disks protect the bones by absorbing the shocks from daily activities like walking, lifting, and twisting. Each disk has two parts—a soft, gelatinous inner portion (nucleus pulposus) and a tough outer ring (annulus fibrosis) . Together, the vertebrae and discs form a tunnel through which the spinal cords and nerve pass.

The aetiology/cause of slip disc is multifactorial, there is no evidence to prove/disprove the quantitative effect of one or other. The risk factors for slip disc can be:

• Ageing : as a part of the normal age related degenerative process.
• Life style: Stress and emotional tension, poor posture -standing for long periods of time or sitting incorrectly—can cause slip disc , heavy physical work, lifting or forceful movement, bending, or awkward positions can really hurt your back.
• Injuries and Accidents : Injury to muscle , ligaments , or soft tissue can lead to slip disc .Fracture in spinal bone in a fall or a car accident also is a common cause. If you have osteoporosis, a condition that weakens your bones, you’re much more prone to fracturing a bone.
• Obesity :Being overweight puts pressure and stress on the back, especially the low back. Carrying excess weight aggravates other health conditions such as osteoporosis (weak bones), osteoarthritis (joint pain), rheumatoid arthritis (an autoimmune disease), degenerative disc disease (described above in the aging section), spinal stenosis, and spondylolisthesis.