The Sciatic Nerve
Structure of the sciatic nerve:
The sciatic nerve is present in humans and other animals. The nerve that passes all the way through the lower back and innervates the lower extremities. It runs through the buttock and goes into the lower limb. It is the nerve that is the longest and widest in diameter and runs all the way through the leg to the foot. This nerve is the mean by which nerve innervation is provided to the legs and feet. The skin of the legs, the muscles in the legs including those of the back and the thigh are innervated by this nerve.
The sciatic nerve has its origin from the sacral segment of the spinal cord. The L4 to S3 segments of the sacral plexus is the collection of nerve fibers from where the sciatic nerve originates. Piriformis muscle is the site where the fibers join and form a single nerve. It travels through the sciatic foramen and end up into the gluteal region.
The nerve divides into two branches at the popliteal fossa:
- Tibial nerve
- Common peroneal nerve or fibular nerve
The tibial nerve runs through the posterior part of the leg while the Fibular nerve passes and innervates the anterior and lateral parts of the leg.
Nervous system has three types of nerves that are:
- Mixed nerves
Sciatic nerve is the largest nerve and it has this big advantage of being a mixed nerve having both sensory and motor neurons. This feature enables it to innervate the muscles and simultaneously makes it feel and move. It covers such a large area of the body during its course from the leg to the feet. It supplies the ankle, entire lower leg and muscles of back and thigh.
Clinical importance of sciatic nerve:
Any pain that is associated with the sciatic nerve comes under the division of Sciatica.
The main cause of sciatica is the depression, compression or any injury to the sciatic nerve or the lower back. Lumbar radiculopathy is the term used medically to describe this disease. It is also called radicular pain. The intensity and severity of the pain depends on the region of the body where the spinal nerve is affected or compressed. The nerve is highly sensitive and herniated disc can lead to the sciatic pain. These discs easily irritate the L1 and S3 segments of the spinal cord. As proteins are present in these nerves, so inflammatory response is produced very easily by the herniated discs. The pains are felt in the lower back, thigh and may extend to the feet.
Sciatica is pain, numbness or tingling sensation that is located at the back or buttocks and radiates to the leg and foot caused by irritation of the sciatic nerve. It is a common affliction because of the uniqueness of the sciatic nerve; it is the largest and longest nerve in the human body so it is prone to irritation or injury along its course either from muscle compression or other disorders affecting the hip or lower back.
The sciatic nerve is formed by spinal nerves of the Lumbosacral Plexus (L4 to S3). The nerve contains both anterior and posterior fibers; it emerges from the sacral part of the spinal cord. It is also important to note that the sciatic nerve also supplies sensation to all parts of the human leg except the inner aspect, it extends from the lower back and runs through the buttocks and down to the lower limbs.
This is normally caused by compression of the sciatic nerve and most hip and lower back disorders have been implicated such as:
- Stabs and wounds
- Fractures of the pelvis or pelvic region
- Wrong administration of injections in the muscles of the gluteal region
- Spinal disc herniation
- Lumbar Spinal Stenosis (narrowing of the spinal canal)
- Piriformis syndrome
- Most degenerative disc diseases
- Ruptured disc
- Bone spurs from arthritis
Other causes include coughing and sneezing, muscular hypertension, tumors or even pregnancy.
IM injections in the sciatic nerve:
Since some drugs are best absorbed via parenteral routes and oral administration might lead to the degradation of the drug and therapeutic uses might not be fulfilled, so IM or IV route are preferred. Injections are administered in the muscles of the gluteal region. It is important to understand the surface markings of the sciatic nerve in the gluteal region.
Course of sciatic pain:
Sciatica is not a medical diagnosis but it indicated the diagnosis of the disease that is lying underneath. Sciatica is rare in children and teenagers. People in middle ages like 20-40 and elderly in 60 years of age has complained of experiencing it more than normal. Sine little knowledge is available in this topic, so we connect every leg pain to sciatica even though it could just be muscle stretch. Recent studies and surveys have shown that 43% of the world population might get affected by this disease in near future or in some point in future.
Sciatica is often described as a sharp excruciating pain sometimes debilitating and prevents the sufferer from getting up if lying down, the pain usually begins in the lower back region or buttocks and extends to the leg or foot. It could present with a feeling of numbness, tingly sensation or weakness of the affected leg. Sciatica is usually worsened by movements which cause flexion of the spine such as knee to chest exercises; other aggravating factors include prolonged standing or sitting.
The pain is often relieved by lying down, walking or executing movement which causes extension of the spine such as press up. Sciatica is usually diagnosed by a doctor after taking the complaint, medical history and physical examination. The doctor will usually order an investigation to determine the cause of sciatica or to rule out other possible causes or problems; such investigation includes X-ray, Computed tomography (CT) scan and Magnetic resonance imaging(MRI) scan.
Thus, in short, the symptoms included are:
- Numbness of the leg and feet
- Burning and itching sensations
- Difficulty in moving and lying down
- Occurs mostly in one leg
- The pain could be mild to severe
- Electric like pain is felt
- Standing or sitting might worsen the pain
Types of Sciatic nerve pain:
Sciatica occurs when damage is done to the sciatic nerve. Types of pain depend upon the area at which the pain is originating. Here are a few examples:
·from L4 nerve root:
Sciatica in the L3-L4 segments of the sacrum shows following symptoms:
Pain and numbness in the middle and lower portion of the leg, difficulty in moving the foot upward and downward and patient experiences inability of knee-jerk reflex.
·from L5 nerve root:
That shows following signs and symptoms:
The big toe and the foot at the place of ankle are mostly affected in this case leading to foot drop. The web of big toe and second toe are affected and pain originates in the lower back. The foot might experience numbness.
·from S1 nerve root:
The symptoms in this section of the sciatica pain involve pain in the lateral and posterior part of the foot and ankle-jerk reflex is affected. Difficulty in raising the heel and walking on the ground is seen.
These pathological features are seen in the sciatic pain. Anatomical features may vary from person to person.
Conditions that lead to sciatic pain:
A variety of causes of the lower back might cause sciatica that includes spinal stenosis, disc slip, osteophytes and arthritis.
Conditions that seem like sciatica:
As sciatica effect the lower back, there are other diseases that have same symptoms as that of sciatica. These include:
·Sacroiliac joint dysfunction:
Symptoms of the sacroiliac joint dysfunction are the same as that of sciatica. The electric pain, numbness of the feet and difficulty in movement are the symptoms that might lead to the wrong diagnosis of sciatica.
·Pressure exerted by the Piriformis muscle:
Piriformis syndrome might occur as the Piriformis muscle exerts pressure on the sacroiliac joint. The symptoms are relatively obvious and quite similar to sciatica. These symptoms include the pain and itching in the legs, numbness of the feet and lower back disorders.
Sciatica could be a medical emergency:
There are few symptoms that indicate that immediate medical care is needed. In case of negligence, life critical situations may occur. Here is a detail of the symptoms:
Cauda Equina Syndrome:
Problems in controlling the bladder and bowel lead to this syndrome. There is a progressive loss of sensation in the legs and patient gradually becomes weak. The nerve sac compresses in the lower spine and medical emergency occurs.
Any injury to the back or spine due to fall might lead to nerve damage that can cause numbness of legs and loss of sensation of the pelvic portion. Immediate medical care is needed in such cases. Nerve damage is hard to treat and patient may suffer from paralysis.
Examination of Sciatica:
The following procedure is employed by physician to examine sciatica:
- Determine motion of spine
- Neurological test of lower limb
- Leg straightening test
- Ankle dysfunction test
- Light touch sensation
Sciatic nerve injuries are a medical care condition and it should be treated as early as possible before any other complications develop.
Most individuals with sciatica may not require treatment and the pain goes away after a while, however other cases may require some medication and exercise to relieve the pain.
For initial treatment of sciatica, NSAIDS (Non-steroidal anti-inflammatory drugs) such as ibuprofen or diclofenac are recommended. Acetaminophen (Tylenol) can also be used to relieve sciatica.
A heating pad or ice packs used for 10 – 15 minutes on the affected leg is reported to bring relieve in some cases where this treatment method was applied.
If pains do not subside, the sufferer may require physiotherapy, muscle relaxants or high dose steroids. In some cases, surgery may be considered for some patients if sciatica is not cured after about two to three months of trying out non-surgical cure approaches. The surgery may be performed depending on the cause of the nerve compression.
Certain types of exercises have also been proven to relieve sciatica; exercises which are effective at relieving sciatica are those which cause external rotation or stretch extension of the hip, also they include:
Arm and Leg Lift Exercise
This exercise is very efficient at targeting the erector spinae muscle, hamstring muscles and gluteal or buttocks muscles. This exercise is performed on all fours by placing both the knees and hands on the floor with your arms and thighs parallel to each other and perpendicular to the floor.The knees should be directly under the hips, similarly, the hands should be directly under the shoulders.
The back should be straightened by lifting the opposite arm and leg slowly and extend them out straight and holding them in this straight position for about 10 seconds then slowly return to the starting position before repeating same on the alternate arm and leg and repeat for the desired amount of repetitions or until you begin to feel relief from sciatica. Do not allow the abdominal muscles to relax or the back to sag while performing the arm and leg lift exercise, also do not lift the arm and leg too high but stretch as far as possible from the toes to the tip of the fingers.
Standing Hamstring Stretch Exercise
This is aimed at relieving the pain and tension in the hamstring muscle which is also known as biceps femoris or rear thigh muscle because when this muscle is tight, it may prevent execution of some actions such as sitting up straight, lifting or bending thus leading to improper posture which may cause further problems such as back pain, neck pain in addition to sciatica.
To perform the standing hamstring stretch, place your right leg on an elevated surface such as a table, chair or staircase while standing, Stand tall with your right foot in front of your left foot and your right toes lifted. Bend your left knee slightly and pull your abdominal muscles gently inward, lean forward from your hips, and rest both palms on top of your left thigh for support and balance. Relax the shoulders and keep them down, you should feel a mild pull gradually spread through the back of your leg. Repeat the stretch with your left foot forward.
Kneeling Hip Flexor Stretch Exercise
This exercise is also very effective at relieving sciatica because it works the Iliopsoas muscle otherwise known as hip flexors as well as the inner thigh and hamstring muscles. To perform this exercise for the purpose of relieving sciatica, adopt a standing position then look straight ahead and take a generous step forward with the left foot, then bend the extended knee and transfer your body weight onto the left leg in front. Continue to lower the rest of the body slowly into the lunge until your right knee hovers just above the ground. Your left knee should be directly above your left ankle.
Piriformis Stretch Exercise
Tension within the piriformis muscle causes sciatica so this exercise is effective in relieving tension within the muscle, while lying on your back on a firm surface with your knees bent, raise your right foot and lift it over the left knee while pulling the left leg also towards your knee while the right leg is still in place, do this for about 60 seconds or more.
You could also stretch the piriformis muscle by lying down on your back usually on a firm or hard surface, cross the leg with the sciatica over the other leg without pain with both knees bent a bit, clasp both hands together and place them below the unaffected leg, still with your hands in place under the unaffected leg gently and slowly pull the lower leg up toward your chest, you should maintain this posture until you begin to feel a stretch in your buttocks, try holding for about one minute or until you begin to feel uncomfortable.
Foam Roller Exercise
This involves using a foam roller placed under both thighs while in a sitting position then gradually move the body back and forth. The foam roller exercise can alleviate sciatica by releasing tension in muscles around the sciatic nerve. This exercise can be done for your outer thigh and calf muscles by putting the foam roller on each side of your body then moving back and forth. You can also lie on your stomach with the foam roller under your thighs, roll down from the top of your hip to the top of your knees, each rolling exercise should last up to a minute.
The injury is troubling and discomforting however most individuals will get better within a few weeks on conservative management. It usually affects one leg and engaging in physiotherapy and the exercises recommended in this article could offer tremendous relieve. Be sure to consult a physician if the pain persists or gets worse while on conservative management so as to receive proper management.