Left: Illustration of herniated spinal disc, superior view. Right: MRI showing herniated L5-S1 disc (red arrow tip), sagittal view.<unk>  is generally caused by the compression of lumbar nerves L4 or L5 or sacral nerve S1. Less commonly, sacral nerves S2 or S3 or compression of the<unk> nerve itself may cause<unk> . In 90% of<unk>  cases, this can occur as a result of a spinal disc bulge or herniation. Intervertebral spinal discs consist of an outer anulus fibrosus and an inner nucleus pulposus. The anulus fibrosus forms a rigid ring around the nucleus pulposus early in human development, and the gelatinous contents of the nucleus pulposus are thus contained within the disc. Discs separate the spinal vertebrae, thereby increasing spinal stability and allowing nerve roots to properly exit through the spaces between the vertebrae from the spinal cord. As an individual ages, the anulus fibrosus weakens and becomes less rigid, making it at greater risk for tear. When there is a tear in the anulus fibrosus, the nucleus pulposus may extrude through the tear and press against spinal nerves within the spinal cord, cauda equina, or exiting nerve roots, causing inflammation, numbness, or excruciating pain. Inflammation of spinal tissue can then spread to adjacent facet joints and cause facet syndrome, which is characterized by lower back pain and referred pain in the posterior thigh. Other causes of<unk>  secondary to spinal nerve entrapment include the roughening, enlarging, or misalignment (spondylolisthesis) of vertebrae, or disc degeneration that reduces the diameter of the lateral foramen through which nerve roots exit the spine. When<unk>  is caused by compression of a dorsal nerve root, it is considered a lumbar radiculopathy or radiculitis when accompanied by an inflammatory response.<unk> -like pain prominently focused in the buttocks can also be caused by compression of peripheral sections of the<unk> nerve usually from soft tissue tension in the piriformis or related muscles.
Sciatica
Shingles
Calpainopathy
Epicondylitis
Carpal tunnel syndrome
Balanitis
Distal myopathy
Heel pad syndrome