istmikunärvi

Istmikunärvi, also known as the sciatic nerve, is the longest and thickest nerve in the human body. It originates from the sacral plexus in the lower back, formed by nerve roots from L4 to S3. The istmikunärvi travels down through the buttock, along the back of the thigh, and then branches into the tibial and common fibular nerves in the popliteal fossa behind the knee.

This nerve is primarily responsible for motor function and sensation in the legs and feet. It controls muscles in the thigh, lower leg, and foot, enabling movement such as walking, running, and standing. Sensory information from the back of the thigh, the entire lower leg, and the sole of the foot is transmitted through the istmikunärvi to the brain.

Problems with the istmikunärvi can lead to a condition commonly referred to as sciatica. This is characterized by pain that radiates from the lower back or buttock down the leg, often accompanied by numbness, tingling, or weakness in the affected limb. Common causes of sciatica include herniated discs, spinal stenosis, bone spurs, and piriformis syndrome, where the piriformis muscle irritates the nerve. Treatment for istmikunärvi issues typically involves conservative measures like rest, physical therapy, and pain medication, though in some cases, surgery may be considered.