A small lump or residual part:nubbins of bone or cartilage...
My lump was just a lump, a pea-sized nubbin of nothing-to-worry-about.
Long names get worn down to three-letter nubbins like stones smoothed by a river.
The right postzygapophysis of the more posterior vertebra can be identified; a small nubbin of bone anterolateral to this might represent part of a cervical rib.