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.