What bones are at this joint?
The bones at the trunk are basically the spine in particular the lumbar vertebrae. I'm pretty proud of my skeleton because it actually shows, from the back at least, all thirty-three vertebrae in the spine. These are grouped by region: seven cervical (neck), twelve thoracic (chest), five lumbar (belly or lower back), and then the sacrum and the coccyx. By the way I fixed the ischial tuberosities, the sit bones, on my skeleton's pelvis. Much better.
I guess the ribs and pelvis are also involved, in the sense that various abdominal and back muscles are attached to them; but mostly at the trunk, we are talking about movement of the spine.
What type of joint is this?
Vertebral joints are facet joints.
What body part moves and is moved at this joint?
In sixth grade, I had to write a country report on Poland. Horrifyingly I only got a "good" or possibly even a "fair" (as opposed to my sister's "excellent" two years earlier) largely due to my geographical section in which I painstakingly identified the highlands and lowlands of Poland and mentioned not at all the vast plains in between that really largely make up Poland, I think, I honestly don't remember. It's possible that the plains of Poland have grown in my mind inversely proportional to my failure to recognize them.
Anyway, that part in your middle. Moves itself, and is moved by itself. Also transitively moves attached parts like your top and bottom. Actually basically involved in all of your body's major movements. Hard to talk about, like the plains of Poland.
