The sciatic nerve is the longest nerve in the human body - it stretches from the pelvis to the foot itself. This structure functions as both a sensory and a motor nerve. Various pathological processes involve the sciatic nerve, but the most famous of them most likely is sciatica.
The sciatic nerve(sciatic nerve or ischiadic nerve) is a unique nerve primarily due to its length - it runs along with its branches along the entire length of the lower limb and it is the longest nerve in the human body. Its dimensions are also quite large: the sciatic nerve is 0.5 cm thick and 1.5 cm wide.
The nerve is derived from the sacral plexus. It is created by combining five nerve roots: L4, L5, S1 as well as S2 and S3. The place where these nerve roots connect to form the sciatic nerve is the minor pelvis - the nerve is formed between the lower edge of the piriformis muscle and the posterior edge of the inner obturator muscle, the sacro-spinal ligament and the sciatic spine.
Sciatic nerve: waveform
The sciatic nerve leaves the pelvis through the hypochondrium opening, then it runs over the abdominal muscles of the iliac girdle. In this episode it is covered by the gluteus great muscle. Then - in the upper thigh - the sciatic nerve runs between the posterior thigh muscle group and the great adductor muscle. The nerve then travels to the popliteal fossa, where the sciatic nerve gives off its two branches.
Sciatic nerve: branches
The sciatic nerve has two branches - these are the tibial nerve and the peroneal nerve. Both of them give successive branches, which are branches to the knee joint. The tibial nerve innervates the muscles of the posterior thigh group, the lower leg, and the muscles of the sole of the foot.
The common peroneal nerve is responsible for the innervation of the head of the short biceps muscle of the thigh. In addition, this nerve - or more precisely its branches - is responsible for the innervation of the muscles of the anterior and lateral parts of the shin.
Sciatic nerve: features
The sciatic nerve is a mixed nerve - it has both sensory and motor fibers. It is responsible for receiving sensory stimuli from the foot and from the lower leg (excluding their inner part).
The sensory sensations from the sole of the foot are perceived thanks to the nervetibial nerve, the second branch of the sciatic nerve, i.e. the common peroneal nerve, is responsible for the reception of this type of stimuli from the upper part of the foot and from the aforementioned part of the lower leg.
Additionally, as noted earlier, the sciatic nerve carries motor fibers that supply various muscles in the lower limb.
Sciatic nerve: diseases
Damage to the components of the sciatic nerve may result in very clearly perceived consequences - probably the most famous disease of the sciatic nerve is sciatica.
This problem most often develops due to pressure on the nerve roots in the spinal canal by part of the intervertebral disc. However, sciatica can also occur in connection with narrowing of the spinal canal and excessive tension in some muscles.
A patient who develops sciatica is usually aware of it - its symptoms are very severe and may include pain radiating from the lumbosacral spine to the foot, sensory disturbances and muscle weakness.
Other problems that can lead to sciatic nerve dysfunction are injuries. They can happen during various accidents (especially in traffic). However, there is also a risk of damage to the sciatic nerve during some surgical procedures. An example is hip arthroplasty.
This complication is relatively rare. However, it is possible and in this case the sciatic nerve may be paralyzed. Symptoms of this problem are gait disturbances (in the case of sciatic nerve paralysis, outward rotation in the hip joint and bending in the knee joint are difficult, in addition, various movements of the foot are abolished). A patient with a paralyzed sciatic nerve moves as if on stilts, and his foot glides along the ground.
Another medical procedure that can damage the sciatic nerve are intramuscular injections - the problem may occur in the event of an incorrectly performed injection in the buttocks and may result in sensory disturbances.
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