1. A method of operating a medical imaging apparatus, the method comprising: acquiring three-dimensional (3D) volume data about an object; generating a 3D image based on the 3D volume data; extracting a muscle tissue figure corresponding to a muscle tissue shape of the object by grouping voxels included in the 3D image; analyzing a motion of the object based on the extracted muscle tissue figure; and displaying the extracted muscle tissue figure and a result of the analysis, wherein the extracting of the muscle tissue figure comprises connecting a first point where a first voxel included in the 3D image is located in n-th frame data, a second point where the first voxel is located in (n+1)-th frame data, and a third point where a second voxel located at the second point in n-th frame data is located in (n+1)-th frame data.