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Nursing and Allied Health: Diseases and Conditions

Online Learning

Welcome to the NSU CON-SAH Library


What is MeSH?

What is MeSH?

MeSH is the acronym for Medical Subject Headings. MEDLINE uses a controlled vocabulary, meaning that there is a specific set of terms used to describe each article. Each MeSH term represents a single concept used in the biomedical literature. Familiarity with this vocabulary will make you a better PubMed searcher, as the best way to search PubMed is to use MeSH terms. MeSH imposes uniformity and consistency to the indexing of biomedical literature. MeSH terms are arranged in a hierarchical categorised manner called MeSH Tree Structures

As the volume and complexity of medical knowledge grow, so too does the language used to describe this knowledge. Finding the right term or keyword to describe a medical condition or problem can be daunting. The Medical Subject Headings database (or MeSH for short) is designed to help you focus your search, and to avoid ambiguous terms or synonyms, ie. where one word can mean many different things, or where different words are used for the same topic.

Using MeSH, therefore, makes your search

  • more relevant (only articles that relate to the topic you want will be retrieved)
  • more consistent (related subjects are consistently grouped together under the same headings)

You can find the MeSH database at



Mesh Tree Structure

MeSH Descriptors


MeSH descriptors are organized in 16 categories: category A for anatomic terms, category B for organisms, C for diseases, D for drugs and chemicals, etc. Each category is further divided into subcategories. Within each subcategory, descriptors are arrayed hierarchically from most general to most specific in up to thirteen hierarchical levels. Because of the branching structure of the hierarchies, these lists are sometimes referred to as "trees".

Pathological Conditions

Pathological Conditions & Processes


MeSH Tree Structure

MeSH Trees


You will see that the MeSH "trees" are represented by a picture of trees on the homepage of the database. The MeSH Tree is composed of many different biomedical concepts, as well as many non-clinical topics. The branches of the MeSH Tree represent many different types of relationships. Each branch represents a set of complex hierarchical terms which become increasingly specific (or narrow) as the hierarchy develops relationships between terms. Headings are positioned in the tree according to their relationship to other headings. 

MeSH vocabulary is 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


Types of MeSH Headings

MeSH Controlled Vocabulary

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.