Meaning of the Sanskrit Word: janubhyam

  jānubhyām—on the ankles    SB 2.5.40-41
  jānubhyām—with its two knees    SB 8.11.15
  jānubhyām—by the strength of Their knees    SB 10.8.21

Can't find any compound Sanskrit words containing janubhyam.