<Table> <Tr> <Th_colspan="2"> Piriformis muscle </Th> </Tr> <Tr> <Td_colspan="2"> Buttocks seen from behind (the piriformis and the rest of the lateral rotator group are visible) </Td> </Tr> <Tr> <Td_colspan="2"> Muscles of the gluteal and posterior femoral regions seen from the front . </Td> </Tr> <Tr> <Th_colspan="2"> Details </Th> </Tr> <Tr> <Th> Origin </Th> <Td> Sacrum </Td> </Tr> <Tr> <Th> Insertion </Th> <Td> Greater trochanter </Td> </Tr> <Tr> <Th> Artery </Th> <Td> Inferior gluteal, lateral sacral and superior gluteal artery, </Td> </Tr> <Tr> <Th> Nerve </Th> <Td> Nerve to the piriformis (L5, S1, and S2) </Td> </Tr> <Tr> <Th> Actions </Th> <Td> External rotator of the thigh </Td> </Tr> <Tr> <Th_colspan="2"> Identifiers </Th> </Tr> <Tr> <Th> Latin </Th> <Td> Musculus piriformis </Td> </Tr> <Tr> <Th> Dorlands / Elsevier </Th> <Td> m_22 / 12550205 </Td> </Tr> <Tr> <Th> TA </Th> <Td> A04. 7.02. 011 </Td> </Tr> <Tr> <Th> FMA </Th> <Td> 19082 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terms of muscle (edit on Wikidata) </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Piriformis muscle </Th> </Tr>

What are the concentric actions of the piriformis muscle