The sciatic nerve runs in the same location in women and men: it starts in the lower back, passes deep through the buttock, and travels down the back of each leg. It is the thickest nerve in the human body, formed by nerve roots branching from the lowest part of the spine (levels L4 through S3). While the nerve’s position is identical regardless of sex, women face several unique conditions that can irritate or compress it, including pregnancy-related changes and endometriosis.
Where the Nerve Starts
Five nerve roots in your lower spine merge to form the sciatic nerve. These roots exit from the lumbar and sacral vertebrae, roughly from your waistline down to your tailbone. The individual roots weave together into a single thick cord that then passes out of the pelvis through an opening called the greater sciatic foramen, a bony gap near the base of your hip. The nerve emerges just below a deep muscle in the buttock called the piriformis.
Its Path Down the Leg
Once the sciatic nerve exits the pelvis, it sits deep in the center of your buttock, roughly midway between the bony point you sit on (the ischial tuberosity) and the bony bump at the top outer edge of your hip. If you were to draw a line between those two landmarks, the nerve would cross near the middle. From there, it travels straight down the back of the thigh, running beneath the hamstring muscles.
Just above the back of the knee, the nerve splits into two branches. One continues down the back of the calf, and the other wraps around the outer side of the knee and runs along the front and side of the lower leg. Together, these branches supply sensation and muscle control to nearly everything below the knee, including the foot and toes. This is why a problem at the hip or buttock can cause symptoms all the way down to your feet.
The Piriformis Connection
The piriformis muscle is a small, deep rotator in the buttock that sits right on top of the sciatic nerve. In about 90% of people, the nerve passes as a single bundle directly beneath this muscle. But in roughly 10% of the population, the nerve takes an unusual route: it may split and pass partially through the piriformis, or travel above it entirely. These anatomical variations can make the nerve more vulnerable to compression when the piriformis tightens or spasms, a condition sometimes called piriformis syndrome.
Women may be more prone to piriformis syndrome because of differences in pelvic biomechanics. The wider female pelvis changes the angle of pull on the piriformis muscle, which can increase tension on the nerve during activities like sitting, climbing stairs, or running.
Pregnancy and the Sciatic Nerve
Sciatica during pregnancy is common and has specific anatomical causes. The hormone relaxin, which loosens ligaments to prepare for delivery, peaks during the first trimester and remains elevated throughout pregnancy. This loosening shifts the body’s center of gravity and changes how forces are distributed across the pelvis and lower spine. The result can be direct irritation or pinching of the sciatic nerve.
As the uterus grows, it also adds weight that increases pressure on the lumbar spine. In some cases, the baby’s head can press against the nerve roots as it descends into the pelvis during the third trimester. The combination of relaxin, weight changes, and postural shifts makes pregnancy one of the most common reasons women specifically experience sciatica.
Endometriosis and Cyclic Sciatica
One cause of sciatica that is entirely unique to women is endometriosis involving the sciatic nerve. When endometrial tissue grows on or near the nerve, it causes a distinctive pattern called catamenial sciatica, meaning the leg pain follows the menstrual cycle. Pain typically starts around day four of menstruation and lasts about a week, radiating from the buttock down the back or side of the leg to the foot.
Over time, the pattern worsens. Repeated monthly bleeding into the tissue surrounding the nerve triggers inflammation, scarring, and fibrosis that gradually compresses the nerve more severely. The pain-free window between periods gets shorter, and eventually the pain can become constant, though it still flares significantly during menstruation. Advanced cases can cause numbness, muscle weakness in the leg, and changes in walking. One reported case involved a 29-year-old woman whose delayed diagnosis led to limping and significant gait changes.
This form of endometriosis can occur in complete isolation, with no detectable endometriosis elsewhere in the pelvis. That makes it easy to miss. If your sciatica consistently worsens around your period, it’s worth raising this possibility with your provider.
What Sciatic Pain Feels Like
Because the sciatic nerve supplies such a large territory, the pain it produces is distinctive. True sciatica radiates below the knee. You might feel it as a sharp, burning, or electric sensation running from the buttock down the back of the thigh and into the calf, ankle, or foot. Some people experience numbness, tingling, or a feeling of weakness in the affected leg instead of (or along with) pain.
A simple check that clinicians use is the straight leg raise: lying on your back and having someone slowly lift your leg while keeping the knee straight. If this reproduces your radiating leg pain when the leg is raised between 30 and 70 degrees, it suggests the sciatic nerve is being compressed. Pain only in the lower back, or pain that doesn’t start until the leg is raised past 70 degrees, points to other causes like tight hamstrings rather than true nerve involvement.
How to Locate It on Your Body
You can’t feel the sciatic nerve through the skin the way you might feel a tendon, but you can map its general location using landmarks you can touch. Start by finding the bony point you sit on (deep in the lower buttock) and the bony prominence at the top of your hip on the back side. The nerve runs roughly between these two points, deep beneath the gluteal muscles. From there, trace a line straight down the center of the back of your thigh to just above the crease behind your knee. That line follows the nerve’s course.
If you’ve ever felt a deep ache or shooting pain along that line, especially one that extends past the knee into the calf or foot, you’ve felt what sciatic nerve irritation produces. The nerve is thick enough at its widest point in the upper thigh that its cross-sectional area measures roughly half a square centimeter, about the width of a thumb. It narrows as it travels down the leg toward its split point behind the knee.