Overall you have the jist of it, but there's a few minor issues with nearly each muscle group which keep it from looking naturalized.
Whenever you sculpt an anatomy study, you need to be mindful of the boney landmarks.
The Acromion Process is a rectangular landmark you will see on the surface of any build regardless of fat muscular or skinny.
The Acromion is where the several surrounding muscles insert (Trapezius) or originate (Deltoid). Currently the acromion looks both mis-placed, and the trapezius is covering too much of it.
Not gonna go too much in depth with the pectorals (But seeing as you've made striations to show the 3 heads of the deltoid):
The way a pectoral is formed, is there are 3 parts to it:
Clavicular head of the Pectoral (Attaches to the Clavicle)
Sternal (Attaches to the Sternum)
Costal (attaches to the Costal cartilege)
All of these 'heads' of the pectoral attach to the of the Humerus. But the Costal head of the Pectoral attaches to a higher part of the Humerus, the Sternal goes to the more middle, and the Clavicular overlaps them, and attaches to a lower part of the humerus:
The sternum is actually 2-bones at childhood. The top part is the menubrium (which fuses to the sternum when you're 5).
This location has a notable divot, and forms a very noticable striation.
Most of your muscles seem to be 'surface correct' but maybe needs a bit more focus on the skeletal structure.
