Higher up on the distal (outer) portion of the spine, the bone surface is smoother.

As the cartilage wears down, the bone surfaces rub against each other.

If the bone surface has bumps or ridges, that means it belongs to a young person.

They cover all of the available bone surface and function as a barrier for certain ions.

These lacunae, or resorption pits, are left behind after the breakdown of the bone surface.

On the bone surface he could just about make out a small groove, or pit, maybe about half an inch long.

He pointed to several places on the bone surfaces where the exterior seemed to be flaking off like old paint.

Behind the level of the eye sockets the caputegulae fuse into a single bone surface.

There is also a radial pattern of grooves on some bone surfaces.

This allows the 2 bone surfaces to rub together.