Peripheral nerve trunks are not rigidly fixed to surrounding tissues along their course. They slide longitudinally in their beds over several millimeters with movements of the extremity. This concept of peripheral nerve excurisions helps to explain the pathophysiological events occurring in entrapment neuropathy, chronic nerve irritation and nerve compression. Although this is an important physiological phenomenon, this has not been examined precisely.
We examined excursion of the normal sciatic nerves of 10 adult rabbits. The following were investigated:
1) Percentage elongation of the sciatic nerve under nomal lower limb motion.
2) Excursion between epineurium and gliding floor.
3) Excursion between the funiculus.
4) Morphological changes of the sciatic nerves under nomal lower limb motion.
5) Microanatomical features of the peripheral nerves adapting movements of the extremity.
The results were as follows:
1) Total percentage elongation of the sciatic nerve was 5.8% in 0° flexion of the knee and 90° flexion of the hip joint. But near the knee joint, the maximum percentage was 9.2%.
2) Excursion was found between the epineurium and gliding floor, and between the funiculus.
3) It was proven that in the funiculus the nerve fibres have an undulating spiral pattern, which is, after its discoverer, called Fontana's bands. When the nerve was stretched in the course of movement, the undulation straightened out until it disappeared. Microanatomical view represents the wave-like alignment of the nerve fibres.
By these features, peripheral nerves can accommodate limb motion.