Anatomy of sciatic nerve
Sciatic nerve is the largest nerve in the body, it’s made up of several spinal nerves that coverage and run from low back to knee. “From L4_S3”
it moves from the lumbosacral plexus in the lower back and sacrum, through the greater sciatic foramen, into the gluteal region, posterior thigh, splitting into tibial and common peroneal nerves that run into the calf, anterior and lateral compartment of the leg, and then into the foot.
Branches of sciatic nerve
- Articular branch: proximally arises to supply the hip joint through the posterior capsule.
- Muscular branch: supply hamstring muscle and ischial part of adductor magnus.
- Distal terminal branch is the Tibial nerve and Common peroneal nerve.
Dermatomes of the sciatic nerve: “sensory innervation”
It’s an area of skin that is supplied by a single spinal nerve. From (L4-S3).
- L4 >> anteriorly curves from the lateral aspect of the thigh to the medial aspect of the leg and foot. Includes the knee, medial surface of big toe, and medial malleolus
- L5 >> posterolateral aspect of the thigh wrapping anteriorly at the level of the knee to cover the anterolateral aspect of the leg.
- S1 >> extend the posterolateral aspect of thigh, popliteal region, and leg to the lateral malleolus, then lateral margin of foot, heel, and little toe
- S2 >> extend from the buttocks to the posteromedial aspect of the thigh, popliteal region and leg.
- S3 >> posteriorly include the medial aspect of buttocks, and perineal area.
Myotomes of the sciatic nerve: “motor innervation”
Motor pathways of the sciatic nerve.” According to nerve roots”
- L4: Ankle Dorsiflexion
- L5: Big toe extension
- S1: Ankle plantar flexion and eversion/knee flexion
- S2: Flexion at the knee
Definition of Sciatica
Sciatica is a pain, numbness, or tingling down the back of the leg that originates in the back and spreads to the hip, buttocks, and the leg.
Why is it called Sciatica?
Due to a problem or compression on the sciatic nerve.
Clinical Notes:
- Common in females more than males.
- Often occurs after age 40 years.
- Rarely occurs before age 20.
- It’s Not a disease, it’s a symptom.
Causes of Sciatica:
Herniated disc :
Disc acts as cushions between the vertebrae. These disks get weaker as you get older and become more susceptible to injury.
The gel-like center of a disc sometimes pushes through the outer lining and presses on the roots of the sciatic nerve.
- Spinal Stenosis :
The nature of wear and tear of the vertebrae may lead to narrowing of the spinal canal. This narrowing, called spinal stenosis, may put pressure on the roots of the sciatic nerve.
- Spondylolisthesis:
It’s a slippage of one vertebra, so that it is out of line with the one above it, narrowing the opening through which the nerve exits. So the extended spinal bones may pinch the sciatic nerve.
- Spinal Tumor :
In rare cases, sciatica may result from tumors growing inside or along the spinal cord or sciatic nerve. When a tumor grows, it can increase pressure on the nerves that branch off from the spinal cord.
- Inflammation.
- Infection.
- Injury, such as a fracture.
- Piriformis Syndrome:
Piriformis is a muscle located deep inside the buttocks. It connects between the lower spine and the upper thigh bone and goes directly over the sciatic nerve.
- If this muscle goes into a spasm, it can make a pressure on the sciatic nerve, triggering symptoms of sciatica.
- Piriformis syndrome is more common in women.
- A Fat Wallet Can Trigger Piriformis.
This condition can affect men who wear the wallet in the back pocket of their pants. This leads to chronic pressure on the piriformis muscle and can aggravate the sciatic nerve over time.
Hint: you can avoid this problem by keeping your wallet in a front pocket or jacket pocket.
Risk Factors
- Age:
Related changes due to age in the spine, like herniated disks, are the most common causes of sciatica.
- Obesity:
Due to increasing the stress on the spine, extra body weight can contribute to the spinal changes that evocate sciatica.
- Occupation:
A job that requires to twist the back, carry heavy loads or drive a motor vehicle for long periods may play a role in sciatica.
- Prolonged sitting.
People who sit for long periods or have a sedentary lifestyle are likely to develop sciatica more than active people.
5. Diabetes.
This condition, which affects the way the body uses blood sugar, increases risk of nerve damage.
6. Pregnancy.
Signs and Symptoms :
How do I know it’s sciatica?
- Pain:
constant burning, tingling sensation or a shooting pain starting in the lower back or buttock and radiating down the front or back of the thigh and leg and feet.
- Numbness: in the back of the leg.
- One-sided symptoms:
Sciatica usually affects one leg.” Patient feels heaviness in the affected leg”.
**Rarely, both legs may be affected together.
- Posture induced symptoms:
Symptoms of sciatica may feel worse while sitting, trying to stand up, bending the spine forward, twisting the spine, lying down, and while coughing.
- The symptoms can be relieved while walking.
Investigations
1. X-ray.
2. MRI.
3. CT Scan.
4. EMG: measures how fast nerve signals travel through the body.
Special Tests
- Straight Leg Raising
2. Slump Test :
Treatment and management :
How long does sciatica usually last?
Most patients (90%) with sciatica get better spontaneously with time, days or weeks with self care treatments.
What are two forms of treatment for sciatica?
Surgical
in severe cases with No response to Physical therapy management.
- Laminectomy: with spinal stenosis .
- Microdiscectomy: with lumbar disc herniation .
Physical Therapy Treatment
- In Acute stage ( pain management) .
- Tens.
- Ice.
- Anti-inflammatory drugs: like, Naproxen Brufen
- Subacute stage:
- Positioning exercise ( flexion or extension position).
- Strengthening and Stretching.
- Piriformis foam roll.
- Supine Piriformis stretch.
- Supine sciatic nerve gliding.
- Prone press up.
- Acupuncture.
- Massage.
- Hot Packs.
- Manipulation and Mobilization.
- Stretch for Piriformis muscle.
- Gait Training.
- Muscle Energy technique
- Mckenzie approach.
Conclusion
Sciatica is caused by an injury, irritation, inflammation, pinching or even compression of a sciatic nerve in the lower back. The most common cause is a herniated or slipped disc that will cause pressure on the nerve root.
References
- Mayo clinic staff. (2022, September 13). Sciatica. Mayo Clinic. Retrieved February 15, 2023, from https://www.mayoclinic.org/diseases-conditions/sciatica/symptoms-causes/syc-20377435
- Prudden, G. (n.d.). Sciatic nerve. Physiopedia. Retrieved February 15, 2023, from https://www.physio-pedia.com/Sciatic_Nerve
- Mayo Clinic staff. (2022, September 13). Sciatica. Mayo Clinic. Retrieved February 15, 2023, from https://www.mayoclinic.org/diseases-conditions/sciatica/symptoms-causes/syc-20377435
- Cleveland Clinic medical professional. (2020, March 25). Sciatica: Causes, symptoms, treatment, Prevention & Pain Relief. Cleveland Clinic. Retrieved February 15, 2023, from https://my.clevelandclinic.org/health/diseases/12792-sciatica
- Stephen Hochschuler, M. D. P.-R. B. D. H. (2023). What you need to know about sciatica. Spine-health. Retrieved February 15, 2023, from https://www.spine-health.com/conditions/sciatica/what-you-need-know-about-sciatica
