It sounds as though you want to have 3 separate items inside of a single cell; text at the top of the cell, text at the bottom of the cell, and then a picture in the middle of the cell. I am no expert, but to my knowledge that is not possible (someone please correct me if I am wrong.) I also cannot figure out how to put a picture inside of a cell itself.
I do have a way to accomplish the end result so long as what you need is the final look and not a useable table in numbers.
Create 2-3 cells for each element. (The middle cell, unless you can put pictures in a cell and I don't know, would just be there for peace of mind, but would hold the picture if you can, I would just do two if the pictures are to be in front of the cell anyway.) The top cell align text to top on the Text tab of the inspector. The bottom cell, align text to bottom on the same tab. Then place the picture in the middle. Now, you have what you want except there is one or two lines dividing the cells. To get rid of this, either click the middle cell if you have one, or the top or bottom cell. Click on the Cell tab of the inspector. Select the bottom border and/or top border button and select "No Border" under border styles. To make this fast, select a full row at a time, or use command click to select all of the same type of rows (middle, top, or bottom) and change all cells at once.
I hope this helps. Best of luck!
~Bret