A skeletal diagram is a picture or illustration of an organism's bones, usually arranged based on its skeletal anatomy. Most skeletal diagrams depict the human skeleton because of the medical and scientific relevance, but diagrams of other organisms are also used in some fields. A skeletal diagram may be used as a simple, quick reference for those who are familiar with the skeleton, or it may be used as a study tool by people attempting to memorize the names and locations of the various bones of the body. Such illustrations are also present in almost all books of anatomy, as bone structure is one of the major determinants of the shape and action of an organism.
The most common type of human skeletal diagram depicts the human skeleton standing straight up and facing forward. Many also include a back view and a side view of the skeleton, as it is not possible to clearly see all of the bones from the front. Other diagrams may depict the skeleton sitting down or engaging in some form of activity, such as walking or swimming. These alternate views are used to demonstrate how the bones appear when they are in motion. A skeletal diagram with alternate views may also make memorization of the bones somewhat easier by showing how they look from different angles and in different states of motion.
While all or most of the bones on a skeletal diagram are usually labeled, some diagrams, particularly those used by students learning the names and locations of the bones, do not include labels. Students are able to write the names of the bones themselves before comparing their diagrams to another skeletal diagram that does include labeled bones. Repeating this exercise is one of the most common methods used by students seeking to memorize the names of each of the bones.
Some computer programs and websites provide interactive skeletal diagrams that often also include information about muscles, nerves, and other aspects of anatomy. One may be able to manipulate the bones and joints on a skeletal diagram in order to see how the skeleton appears in various postures. Some such programs allow the user to view "layers" of human anatomy. After arranging the skeletal diagram in a certain way, for instance, one could choose to view the muscle and skin as well. Computerized anatomy programs and skeletal diagrams are useful because they usually allow the user to rotate the skeleton to any angle and to seek further information about any bone of interest.