Sciatic Nerve is the major nerve of the leg and the nerve with the largest diameter in the body. It is formed by the coming together of five nerve roots exiting the lower spine. The sciatic nerve runs downs behind the thigh and divides into two main nerve branches, the tibial and common peroneal nerves. These nerves give motor control and sensation to the lower leg.
Sciatica is pain felt down the back and outer side of the thigh, leg, and foot. It is usually caused by degeneration of the intervertebral disc that bulges out to compress a nerve root exiting the lower lumbar or upper sacral spine.
Vertebra is one of the 33 bones that make up the spinal skeleton. When referring to more than one vertebra you say vertebrae. Each vertebra consists of a body with arches of bone coming from it to from a passage way for the spinal cord. Spinus processes extend like arms from the vertebra to act as attachment points for facet joints and muscles of the spine.
Intervertebral Disc is the flexible plate of fibrocartilage that connects any two adjacent vertebrae in the spinal skeleton. When we are infants the central part of the disc (the nucleus pulposus) consists of a gelatinous substance that can dry out as we age. These discs act as shock absorbers, protecting the spinal cord and brain from the impact produced by running and other movements.
Herniated Disc, bulging disc, or prolapsed disc is the protrusion of the gel-like inner material of an intervertebral disc against or through the fibrous outer coat. This will cause pressure on adjacent nerve roots. Herniated disc is also known as “slipped disc” but is a misnomer in that an intervertebral disc cannot slip out as it is firmly attached to bony vertebrae. Bulging of the disc material can happen as a result of sudden twisting or bending of the spine or lifting. Pressure on the sciatic nerve root causes sciatica and if severe may damage the nerve’s function, leading to loss of sensation, muscle weakness, or loss of tendon reflexes.
Osteoarthritis is a degenerative disease of joints resulting from wear of the articular cartilage, which may lead to degenerative changes in underlying bone like abnormal bone growth or inflammation. It can occur after abnormal load to the joint causing increased wear. The joints are painful and stiff with restricted movement. On X-ray the evidence of loss of cartilage is evident by narrowing of the joint space and the presence of osteophytes, osteosclerosis and cysts in the bone.
Facet Syndrome is the wearing down of the joints in the spine which are called facet joints. This can lead to osteoarthritis and/or spondylosis.
Osteophytes are growths of bone that occurs at sites of cartilage degeneration or destruction near joints and intervertebral discs.
Osteosclerosis is an abnormal increase in the density of bone as a result of poor blood supply, or chronic infection.
Spondylosis is the degeneration of the intervertebral discs in the spine. Symptoms include pain and restriction of movement. Spondylosis appears on X-ray as narrowing of the space occupied by the disc and the presence of osteophytes.
Stenosis is the narrowing of any passage such as abnormal extra bone growth into the spinal canal and putting pressure on the spinal cord (spinal stenosis); or abnormal formation of plaque on the walls of an artery (carotid stenosis).