You can select anatomical structures in the Atlas and Quiz modes, or after hitting the "Pause to Explore" button during an interactive animation in the Show mode, using the following actions:
Selecting a single anatomical structure: To select an anatomical structure, tap it once. The structure is highlighted and its name appears at the top of the screen. A second selection overrides the first selection (unless in Multiple Select mode; see below), so that only one structure at a time is highlighted. To deselect a selected structure, tap on it once.
Selecting multiple anatomical structures: To select multiple anatomical structures, first select a single structure, and then tap on the "Multiple Select" button on the left side of the screen. The Multiple Select mode allows you to select as many structures as you wish by tapping each structure once. All remain highlighted, but only the most recently selected structure selected is named at the top of the screen. To deselect any selected structure, tap on it once. To return to Single Select mode, tap on the "Single Select" button on the left side of the screen.
Selecting an anatomical grouping within the circulatory system: When a structure is selected in Atlas views, a breadcrumb trail displaying its anatomical hierarchy is displayed at the top of the screen. This information includes the structure's location within its system and the name of the system itself (e.g. Circulatory (Cardiovascular) System > Heart > Heart valves > Pulmonary valve). Within the circulatory system, you can use this trail to select any of the larger groupings. Tap once on the desired name in the breadcrumb trail and the associated anatomical structures are selected and highlighted onscreen. The breadcrumb trail also appears for structures outside the circulatory system, but is for informational purposes only.
Deselecting structures: If Multiple Select mode is on, deselect a single structure by tapping on it again, or deselect all structures by tapping the "Deselect All" button on the left side of the screen. If Single Select mode is on, tap on a background area of the screen to deselect a single structure, or tap on the selected structure itself.