PALMAR INTEROSSEI OriginAnt shafts of 1, 2, 4, 5 MCs (unipennate) ActionAdduct to axis of middle finger. Flex MCP jnt whilst extending IP jnts InsertionProx phalanges and dorsal extensor expansion on ulnar side of index and radial side of ring and little fingers and to ulnar sesamoid of thumb NerveDeep br of ulnar N (T1)