the arch or "bridge" of the sole of the foot (see Molina, who seems to put this in the first person plural possessive form; SW)
Alonso de Molina:
toxocpal pichauhyan. la puente dela planta del pie. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 151r. col. 2. Thanks to Joe Campbell for providing the transcription.