transversus perinei superficialis

noun

transversus pe·​rin·​ei su·​per·​fi·​ci·​a·​lis -pe-ˈrin-ē-ˌī-ˌsü-pər-ˌfish-ē-ˈā-ləs 

: a small band of muscle of the urogenital region of the perineum that arises from the ischial tuberosity and that with the contralateral muscle inserts into and acts to stabilize the mass of tissue in the midline between the anus and the penis or vagina

called also superficial transverse perineal muscle