The thumb and the saddle.
D002348:Carpal Bones / Q000033:anatomy & histology*; D006801:Humans; D007596:Joints / Q000033:anatomy & histology*; D008663:Metacarpus / Q000033:anatomy & histology*; D009068:Movement; D012399:Rotation; D013933:Thumb / Q000033:anatomy & histology* / Q000502:physiology