Use the MeSH Browser, an online vocabulary look-up aid, to find MeSH terms in PubMed.
For instance, if you want to search cancer of the jaw, finding the MeSH term will help you narrow down your results. The actual MeSH term is "Jaw Neoplasms" and it is further subdivided into additional categories. Your term may fall under MULTIPLE categories, as in the example below.
You can also use additional subheadings or quantifiers to group together those citations about a particular aspect of a subject.
