Pain along the sciatic nerve is referred to as sciatica when it has been irritated.
The sciatic nerve is the longest and most extensive nerve in the human body.
The nerve endings that make up the sciatic nerve travel all the way down the leg from its origin in the nerve roots of the spinal cord in the low back. These nerve roots are located in the buttock region.
Pain from sciatica can typically be localised in the low back, along the back of the thigh, and all the way down to below the knee.
The most common cause of sciatica is the compression of a nerve in the lower back by a herniated disc, a bone spur on the spine, or a narrowing of the spine (also known as spinal stenosis). This results in inflammation, pain, and frequently a degree of numbness in the leg that is affected.