This is a three-part series on the sciatic nerve. It will include a brief overview of the sciatic nerve anatomy and physiology, causes of sciatic nerve pain (sciatica), and treatments for sciatica.
by: Dr. David Futral
The sciatic nerve is the largest diameter nerve in the human body. This large nerve is called a mixed nerve as it contains both sensory and motor fibers, which is to say it provides sensation input and movement output. The nerve originates from the lumbar and sacral regions of the spine having its roots arise from L4, L5, S1, S2, S3 (L=lumbar spine and S=sacral region.) After leaving the spinal cord, these nerve roots join together, on both the left and right sides, in the gluteal region to form the sciatic nerves.
As the nerve travels down the back of the thigh and lower leg, it supplies motor control to muscle groups along its path. The muscles of the posterior thigh, including the hamstring, all muscles of the lower leg, and all muscles in the foot and ankle are controlled by the sciatic nerve and its branches. Sensation along the lateral (or outside) lower leg, heel, dorsal and plantar (top and bottom) of the foot is relayed by branches of the sciatic nerve.
In summary, the sciatic nerve: is the largest nerve in the body; it and its branches run from the lower back to the feet; it supplies motor control and sensation input to the back of the thighs, lower legs, and feet.
Yours in health,
Dr. David Futral
