## 4 Implementation, Results, and Discussions
### Application Navigation and Features
#### 4.1.3 Main Menu  
When the user chooses their option of interest, they would encounter a main menu that was later incorporated into Build 7 upon the client's request. The main menu allows the user the choice of which features to select among the four key features available (Figure 2(c)): (i) 3D mode (non-immersive functionality); (ii) AR mode (immersive functionality); (iii) Glossary (containing tables with more detailed information on the muscles, bones, and nerves);  
Figure 3: The changes made to the Hub and Main Menu, including final UI design and placement, during application development. and (iv) Quiz (to test user knowledge). The final progression of this menu, including the addition of the application name, Home and Help UI button, is shown in Figure 3.  
The main menu allows access to important features such as the following:  
1. 3D mode non-immersive functionality  
In the 3D mode, using a System Isolation UI button (top-right of mobile screen on Figures 4(b) and 5), the user can interact with either the muscular, skeletal, or nervous components of the 3D models (Figures 4 and 5). Although the application was developed for students to learn the muscular system, according to the client's request, it was decided that the addition of skeletal and nervous system elements would make for a more integrated learning of how muscles work in relation to other anatomical structures. In order to obtain a deeper understanding of the musculoskeletal system, the user can further isolate the musculoskeletal system into various muscle layers or compartments within the musculoskeletal system using a Muscle Layer UI toggle (middle-right of mobile screen in Figure 5). Furthermore, the user can rotate the model using the Rotation UI button (bottom-centre of mobile screen Figure 5), relocated from the Play Animation Figure 5(a), to view the different anatomical positions (anterior, posterior, medial, lateral) with tags displayed top-centre of the screen (Figures 4(b) and 5). Lastly, the 3D mode also contains a Navigation Bar (bottom-left of mobile screen), allowing easier navigation in order to access either the AR mode, 3D mode, Glossary, or Quiz within the option of interest, a Home button (top-left of mobile screen, returns the user to the Hub Menu), and an Animation UI button (bottom-right of mobile screen, which allows access to animations of muscle functionality that the user can observe) (Figure 4). Figure 4: The changes made to the 3D mode, including final UI design and placement, during application development. In APK Build 1, basic proxy non-interactive 3D shapes of various colours were used to differentiate and isolate the respective elements (muscular, skeletal, or nervous) as shown in Figure 3(a). The proxy shapes were later updated to block-out models and subsequently replaced with \"realistic\" models by Build 5 (Figure 3(a,b)). By Build 7, the \"realistic\" models were edited and imported into all of the systems (skeletal and nervous system non-interactive). Similarly, the basic rotating proxy non-interactive 3D shape in the Play Animation section (accessed via an Animation UI button) was updated to a \"realistic\" model in Build 4 (Figure 6). The models were presented in this order so as to provide clients with a functional APK build at the end of each week and demonstrate the \"direction\" in which the application is going. All of the necessary models and information per muscle function were added by Build 9 and updated in Build 10 (Figures 5 and 6). Figure 5: The changes made to the 3D mode, including final UI design and placement, during application development. Figure 6: The changes made to the animation feature, including final UI design and placement, during application development.