The (also known as the '''ischiatic nerve''') is a large
Nerve that runs down the
Lower Limb . It is the longest single nerve in the body.
The sciatic supplies nearly the whole of the skin of the leg, the muscles of the back of the thigh, and those of the leg and foot.
The nerve enters the lower limb by exiting the
Pelvis through the
Greater Sciatic Foramen , below the
Piriformis muscle.
It descends between the
Greater Trochanter of the
Femur and the
Tuberosity Of The Ischium , and along the back of the thigh to about its lower third, where it divides into three large branches, the
Tibial and
Common Peroneal Nerves . This division may take place at any point between the sacral plexus and the lower third of the thigh. When it occurs at the plexus, the common peroneal nerve usually pierces the
Piriformis muscles.
In the upper part of its course, the nerve rests upon the posterior surface of the ischium, the
Nerve To The Quadratus Femoris , the
Obturator Internus and
Gemelli ; it is accompanied by the
Posterior Femoral Cutaneous Nerve and the
Inferior Gluteal Artery , and is covered by the
Gluteus Maximus .
Lower down, it lies upon the
Adductor Magnus , and is crossed obliquely by the long head of the
Biceps Femoris .
The nerve gives off articular and muscular branches.
- The (''rami articulares'') arise from the upper part of the nerve and supply the Hip-joint , perforating the posterior part of its capsule; they are sometimes derived from the Sacral Plexus .
- The (''rami musculares'') are distributed to the following muscles of the lower limb: Biceps Femoris , Semitendinosus , Semimembranosus , and Adductor Magnus . The nerve to the short head of the Biceps femoris comes from the common peroneal part of the sciatic, while the other muscular branches arise from the tibial portion, as may be seen in those cases where there is a high division of the sciatic nerve.
The muscular branch eventually gives off the
Tibial Nerve and
Common Peroneal Nerve , which innervates the muscles of the (lower) leg. The tibial nerve goes on to innervate all muscles of the foot except the extensor digitorum brevis (peroneal nerve).
Pain caused by a compressed or damaged sciatic nerve is called
Sciatica .
