I have this huge old apple tree in my yard. Here are some pictures:

This is a pic of the top of one of the branches. Notice missing bark and
cracks:
http://zootal.no-ip.info/stuff/2006%...s/DSCF3743.jpg
http://zootal.no-ip.info/stuff/2006%...s/DSCF3744.jpg

Trunk:
http://zootal.no-ip.info/stuff/2006%...s/DSCF3745.jpg
http://zootal.no-ip.info/stuff/2006%...s/DSCF3746.jpg

Entire tree:
http://zootal.no-ip.info/stuff/2006%...s/DSCF3750.jpg

The pics may not really give a good indication of the tree's overall health.
The leaves are warped, curled slightly. No new growth. Apples look good, so
far. Some of the branches have missing bark and cracks. I'm not sure how
healthy it is or how long it will live. What can be done to maintain and
improve the health of an old tree like this?