Our ‘Sitting Bones’ are more formally called the ischial tuberosities. These tuberosities are two curved bones, which extend from the ischium in the base of the pelvis. You can see the left one in the photo of Skelly, below.
The weight of our body drops down and is spread through our two sitting bones, which allows us to balance on them. The sitting bones also act like rockers, thus allowing some pelvic movement and change of position and the angle of our posture whilst sitting.
If you wish to know where your sitting bones are, sit in a poised position on a firm surface, with your hip joints free, feet on the floor and then rock from side to side, or back to front. The two knobbly bones you can feel as your weight transfers from buttock to buttock, are your sitting bones.