nerve sciatic nerve BTO:0001221 BrendaTissueOBO The largest nerve of the body: origin, sacral plexus-L4-S3; it leaves the pelvis through the greater sciatic foramen; branches, divides into the tibial and common peroneal nerves, usually in lower third of thigh; distribution-see individual branches, in this table; modality, general sensory and motor. nervus ischiadicus nervus sciaticus