Principal English Translation: 

the ankle of the foot (see Molina); also, the wrist bone (see Sahagún)

Alonso de Molina: 

quequeyolli. touillo del pie.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 89r. col. 1. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

quequeiolli = wrist bones
tomaquequeiol = our wrist bones
ololtic = round
tepitztic = hard
tlaquatl = hardness
cecepoctli = numbness
tlaqualnextia = they show to advantage
quitlacanextia in toma, in maitl = it sets off our hand, the arm (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 10 -- The People, No. 14, Part 11, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 116.