Related for Berakhot 56:20

Rebbi Simon said, corresponding to the 18 bones in the spine since when a person prays he has to bend all of them bowing down. What is the reason? (Ps. 35:10) “All my bones shall say, o Eternal, who is like You?¹⁴¹In the Babli (28b), this reason for the number 18 is given by Rebbi Tanḥum in the name of R. Joshua ben Levi who notes that, when bowing down in prayer, all joints must be moved.”