A good source for background information on medical topics in plain English is MedlinePlus - Health Information from the National Library of Medicine
About MedlinePlus: "MedlinePlus is the National Institutes of Health's Web site for patients and their families and friends. Produced by the National Library of Medicine, the world’s largest medical library, it brings you information about diseases, conditions, and wellness issues in language you can understand. MedlinePlus offers reliable, up-to-date health information, anytime, anywhere, for free."

Primary Sources in science typically report facts about discoveries, observations, experiments and tests. Examples include published results of research studies, scientific experiments and clinical trials, and proceedings of conferences and meetings

Secondary Sources analyze and interpret research results and scientific discoveries. Examples of these include publications about the significance of research or experiments, analyses of clinical trials, and reviews of the results of several experiments or trials.

In the ScienceDirect database, primary and secondary are distinguished by the labels Original Research Article and Review Article, as shown below.

The top three databases for human anatomy topics in this course are PubMed, BIOSIS Previews, and MEDLINE (EBSCO).

These databases contain in-depth articles and information on this subject.