A herniated disc occurs when the soft, gelatinous inner core of a spinal disc leaks out through the disc’s weakened outer layers and affects a nearby nerve.
To help you clearly visualize how a disc herniates and creates pain, we've created this Telly Award-winning animated video.
Herniated disc video highlights
These discs allow for flexibility and movement of the spine, absorbing shock when you move. In the image below, each disc is shown in blue.
Degeneration over time or due to forceful trauma may cause weak spots to form in the outer layers (the annulus fibrosus) of a spinal disc, as shown below.
When weakening of the annulus fibrosus occurs, the soft, gelatinous center (the nucleus pulposus) of the disc can leak out.
When a nerve is compressed by the nucleus pulposus, the herniated disc may begin to become symptomatic.
A closer look at lumbar herniated discs
Your lumbar (lower) spine carries more weight than your thoracic spine (found in the middle and upper back) or cervical spine (found in the neck) and is particularly susceptible to injury.
If your lumbar herniated disc has pinched a nerve, you may experience pain moving down your buttock and into your leg. This type of pain is often referred to as sciatica.
In rare instances, a lumbar herniated disc may cause you to lose control of your bowel or bladder. This lapse of control may be a sign of cauda equina syndrome, a relatively rare but serious medical condition involving dramatic swelling of the nerves at the end of the spinal cord.
A closer look at cervical herniated discs
The cervical spine is found in the neck. Cervical herniated discs are less common than lumbar herniated discs, and are most frequent among people between the ages of 30 and 50.
When a disc in your cervical spine herniates, it can put pressure on an adjacent nerve root, which may cause pain to move along the nerve pathway down your arm.
The pain and neurological symptoms you experience from a cervical herniated disc will depend on the severity and location of the herniated disc.
For example, a cervical herniated disc near the upper middle of your cervical spine (C4-C5) could cause shoulder pain and weakness in your upper arm. A cervical herniated disc at the bottom of the cervical spine (C7-T1), though, might cause numbness, weakness in the grip of your hands, or a painful, tingling sensation that moves down the arm to the outside of your hand, near your little finger.
A closer look at thoracic herniated discs
While less common than lumbar disc herniations, the discs in your thoracic spine (the upper back) can also herniate.
Symptoms of a thoracic herniated disc will correlate with the location of your disc herniation. Thoracic discs can herniate centrally (move backward into your spinal canal), laterally (move to the side of your spine), or centro-laterally (move both backwards and sideways).
If you have a central herniation in the thoracic spine, you’re likely to experience upper back pain and, in rare cases, myelopathy, a compression of the spinal canal in your upper back. Lateral thoracic herniated discs are likely to cause abdominal pain or pain radiating through your chest wall, while centro-lateral herniations of the cervical spine commonly cause upper back pain and radiating chest wall pain.