Contents   Clicking on the Contents button opens up a floating window listing all the objects included in the title. For example:     You can choose to display any number of these objects in the 3D model. Clicking on any of the object categories (e.g. Arteries) will open up a list of objects in that category (i.e. a list of arteries), or a list of subcategories (e.g. Muscles of the tongue), which can in turn be opened by clicking. Close a category or sub-category by clicking on its name again. Alongside each item in the Contents list are four icons: use the x icon to Xray the category, sub-category or object in the 3D model, use the o icon to make an Xrayed category, sub-category or object opaque (i.e. solid) again in the 3D model, use the + icon to add the category, sub-category or object to the 3D model, use the - icon to remove the category, sub-category or object from the 3D model.