First off, do NOT feel like you're dumb or can't learn this. Anatomy is particularly hard for non-science majors and nontrads who've been out of school. I personally failed my first and third anatomy exams (passed the second and fourth by a hair, ending up 0.3% above the passing line) but my first year final mark was just below the class average (would have been above if not for stupid Anatomy).
Here's what you need to do:
1. Go talk to your course director NOW.
2. Tell your dissection group that you're having trouble and you really need help. Have them quiz you as much as possible. You can't really quiz yourself on the body, because how will you know if you're right or not? They will probably be glad to teach you if they know you need extra help, because they know that they can really best solidify their own knowledge by teaching it to someone else.
3. Go talk to your learning/counseling person. Every med school has one or more of these folks, and their job is to help you learn to learn this type of material. They have PhDs in this, which nobody lurking on SDN does. Get your appointment asap.
Suggestion #2 is going to boost your grade the most. Suggestion #1 and #3 will buy you sympathy from the school in case you do fail. Med school teachers have a lot of leeway in many cases-you can fail and with a mark of the pen they can change you to passing, IF they believe you deserve it in spite of your scores.
finally, hang in there. It CAN be done. Even if you repeat Anatomy, you can still be a doctor. Third year will be on you before you know it, and your non-science background will finally start to be a help, not a hindrance.