Can it happen to the drummer to feel himself in corporeal fragments?
Each individual corporeal segment, separated respect to the whole body having to put himself on all the different parts of the instrument.
And at the same time how the drummer can find again his own ‘global reassumption’?
Well, interesting question. One of the things all drummers practice is a thing called “independence”. Where he works on creating different musical patterns with different limbs. He practices this while keeping his body centered. He can then perform these different rhythmic patterns and then improvise some changes in these patterns.
He sounds better if he knows from what pattern or idea he started from. Often the improvisations themselves have to be dissected into patterns that have been pre rehearsed. The biggest question is where, when and why you use certain patterns, ideas or improvisations.
To me, all of this is part of what makes playing drums interesting.

Different parts of body, different limb. And voice. What is for a drummer the relationship with his voice and the breath, lips, mouth vibrations? 
Well, we all have to breathe while we live and perform. Sometimes we may do things that make us hold our breath while we perform (not that it is technically a good thing to do). Sometimes we may also sing the song we are playing or sing to ourselves the basic theme someone is improvising over while we also improvise.
For drummers there are 2 worlds: there is the world of rhythm and percussion, and the world of what is happening melodically.
What we do is apply rhythm to melody. . . the idea is that we understand there is usually a rhythmic component to any melody or at minimum a percussive component. We live in a world which contains both rhythm and melody. Our concentration, for the most part, is the percussive reality.

So the drummer perceives himself as a unique body? 
I would say, yes, that the drummer does perceive himself as a unique body, but this is not different than the other instruments who are also unique bodies in the sound, timbre and function they play in an ensemble or an orchestra.

photo by Mattew Campbell
 
Playing drums happens, also simultaneously, a continuous flowing, passing of different kinds of sounds, from a particular kind to other, a not univocal sound. And different kind of cymbals, of skins, and many different areas for percussion: so material of the instrument itself and perception, perception and connection material, emotion, transmission. A relationship between material-perception-emotion-sound emission-expressivity, and in relation with listening space…
There are many different kinds of drums. Cymbals. Percussion instruments: drum, tympani, piano, guitar, bass, marimba, xylophone. Are all technically considered percussion instruments. All have different material and “a relationship between material-perception-emotion-sound emission-expressivity”. Some of them have a very direct melodic ability, but nevertheless they are considered percussion instruments. This is to say that the different sounds in percussion are very broad, and that the ideas of what a percussionist can do can sometimes be limitless. Some percussion instruments have their limits, but with skill we can point the listeners’ ears in a direction that makes them hear and intuit other instruments and melodies. There are very interesting movements in drum set playing that allow the drummer to use the drumset in an unconventional way using different sticks, bells, electronics, the sides of the drum, odd sounding cymbals, etcetera. Milford Graves and Gino Robair among others, are drummers who have spent a lot of time in this area.