Lumbosacral plexus

The lumbosacral plexus is the connected system of lumbar plexus and sacral plexus pathways formed from anterior spinal nerve rami of lower spinal nerves. It redistributes sensory and motor axons into peripheral nerves supplying the pelvis and lower limb. Its connecting lumbosacral trunk usually carries contributions from L4 and L5 into the sacral plexus.^[ref]

For example, the femoral nerve draws mainly on upper lumbar levels, while the sciatic nerve combines lower lumbar and sacral contributions. A named peripheral nerve consequently does not correspond one-to-one with a spinal nerve. The nerve plexus reroutes existing axons; its intersections do not imply that the fibres form synapses.