Take a close look on the bottom left hand corner of page 18 (Mangastream) and you will notice that the torso is placed on a chair. I am aware that this is a fictional series, but it is impossible for a torso to maintain its balance without the essential mechanisms such as the proprioceptive mechanism and the vetybular system. Propioception is a sense that imforms the organism the possition of the muscles, it is the ability to sense the relative possition of adjoining body parts; The vestybular system is located in the head (that is all you need to know), and without the head/brain (Organ which transmits information to rest of the body) it is literally impossible to maintain balance.
I believe Mutsuki's torso has been placed in the chair. I want to say that it isn't Mutsuki's torso on the the chair, but If it isn't Mutsuki, then why does Urie look so shocked? It also appears as though he is crying. -sigh- It's sad because Urie wants to be the best, he wants to surpass Arima, and yet Shirazu and Mutsuki died on his watch.