MeSH reviewers read articles before they go into MEDLINE and assign appropriate subject headings to the article. These subject headings from a pre-set list (or vocabulary). MeSH applies one term to a collection of concepts - even if that exact term is not used in the article.
Try using the MeSH Browser to locate the best term to search in PubMed
Launching PubMed searches from the MeSH database
To build a PubMed search from MeSH: