MeSH on PubMed: Home

The National Library of Medicine uses a controlled vocabulary to index journals articles, this controlled vocabulary is called MeSH (Medical Subject Headings).

Subject experts assign specific MeSH terms where applicable. MeSH index terms will help ensure that your search results will include articles about your topic, even when different words were used to describe the topic in the title and abstract. 

Subheadings are arranged in logical hierarchical groupings (families). For example:

• therapeutic use
  • administration & dosage
  • adverse effects
  • poisoning

A search of the subheading therapeutic use in PubMed would automatically explode to retrieve citations indexed with the subheadings administration & dosage, adverse effects, and poisoning.

Not all subheadings are placed in these groupings (as they do not logically fit).

The MeSH controlled vocabulary consists of four different types of terms:

• Headings: The main MeSH term.
• Subheadings: Subheadings are used in combination with MeSH headings. They help to further identify a particular aspect of a MeSH concept. For example, the subheading "Therapy" is used with a MeSH term that describes a disease, when the article is about treatment for that disease.
• Publication Types: This describes the type of article that is being indexed, for example, a "Journal Article" or a "Review" or "Clinical Trial".  
• Supplementary Concept Records: Used to identify topics discussed in articles. The majority of these terms represent chemicals and substances that are mentioned in a significant way in an article.

MeSH headings are organized in a "tree" with 16 main branches:

A. Anatomy
B. Organisms
C. Diseases
D. Chemicals and Drugs
E. Analytical, Diagnostic and Therapeutic Techniques and Equipment
F. Psychiatry and Psychology
G. Phenomena and Processes
H. Disciplines and Occupations
I. Anthropology, Education, Sociology and Social Phenomena
J. Technology, Industry, Agriculture
K. Humanities
L. Information Science
M. Named Groups
N. Health Care
V. Publication Characteristics
Z. Geographicals

Each branch has many levels of sub-branches, and each heading has a position in the hierarchy.

• Anatomy
  • Body Regions
    • Torso
      • Back
        • Lumbosacral Region
        • Sacrococcygeal Region

Some terms appear in more than one branch of the tree. For example:

• Anatomy
  • Body Regions
    • Head
      • Ear

• Anatomy
  • Sense Organs
    • Ear
      • Ear, External +
      • Ear, Middle +
      • Ear, Inner +

The hierarchy allows a MEDLINE/PubMed search of a broader term to include the narrower terms in all branches automatically. This is known as "exploding." For example, a search of ear in PubMed would automatically explode to include records indexed with Ear, External; Ear, Middle; and Ear, Inner, as well as all narrower terms under each of these.