It is good to hear that you are interested in learning more. First, I did try to answer your questions, and will try another approach. The ONLY way to 100% verify that a disc is herniated is via a MRI or contrast film that shows such detail. If someone has LBP and leg pain that shoots or has numbness and tingling compared to someone who is without LBP and has the same symptoms, both individuals could have a herniated disc.
Second, most fitness professionals do not really know the importance of the multifidi and where it is located, so I was just reeducating on the obvious to paint a picture. If someone has poor body awareness it still begins with teaching the client how to find neutral spine, how to contact their TVA and then the multifidi. This is the essence of static not dynamic lumbo-pelvic stabilization training.
Few personal trainers have taken courses in human movement science, as the US is far behind compared to Australia. Where Human Movement degrees take place Kinesiology degrees and go in great detail down under.
So to summarize, it begins with a proper assessment after a thorough history which I am sure you are aware of since you were a nurse. Then proper exercise prescription to target the clients’ weak links while helping them achieve their specific goals. But there is not one unique way to begin teaching a client how to strengthen their core except to begin with the basics. Because all individuals have different somatotypes, physical conditioning, different or multiple injuries, age, different jobs, etc.
That is why with I always assess a patient’s ability to contract their TVA, know how to find neutral spine and now really how to properly contract their multifidi.