well if you have neutral pelvis you should start with lower abdominal work. there are NO lower ab muscles, it is just the distal end of the rectus abdominus but there are different nerves going to the portion of the six pack below the belly button.
This allows for segmented contraction of the abs, most other muscles only have 2 nerves, a primary & secondary - the rectus has 8, thus either end can be a prime mover or stabilizer. The function of the lower abs is to work with the external obliques to rotate the pelvis 10 degrees bacwards during movement thus allowing for neutral pelvic alignment and decreasing shear of the lumbar vertabrae.
also you need to remember to activate the transverse abdominus; you would always want to draw the belly button toward the spine to activate the TVA which will also align the pelvis and flatten the abdominal wall ****Note: pulling in your belly button (activating the TVA) is the only way to use muscles to flatten the abs, crunches DO NOT flatten the abdominal wall and if you do crunches without 1st pulling in you can distend the abdomen due to pushing out too hard.
After lower abs, oblique work - rotation & lateral bending and then finally full range forward flexion i.e. crunches.
Lower ab exercises can include: Pelvic tilts, leg lowering, reverse crunche, knee raises
Oblique work includes all forms of rotation: wood chops, russian twist, medicine ball throws etc. & lateral bending: side bridges, cable or dumbell side bends, overhead (Saxon) side bend
Crunches for the upper abs are best done over a physioball for the full ROM of the rectus is 40 deg. extension & 30 deg. flexion meaning if you do crunches on the floor, a bench or machine for too long you will lose 10 degrees of extension/mobility in the thoracic spine.
Although individual testing should be done to determine which muscles are weak so they can be prioritized (usually TVA & lower abs) and then dynamic full range movements using both the rectus & hip flexors can be used.
Believe me it is more detailed than this but I tried to keep it short. Here is a link to the BEST ab book ever!!! and some useful articles:
http://www.amazon.com/exec/obidos/t...f=sr_1_1/002-7519845-4328867?v=glance&s=books
http://www.chekinstitute.com/articles.cfm?select=24
http://www.chekinstitute.com/articles.cfm?select=31
http://www.chekinstitute.com/articles.cfm?select=33
http://www.chekinstitute.com/articles.cfm?select=12
Hope this helps!!
S