>>7779537 (OP)
for the most part, yes. both of those muscles attach medially to the upper part of the humerus which would make it look like it's inserting "into the armpit", but it doesn't necessarily need to be 100% accurate
consider the fact that you, someone studying to become an artist and is paying significant attention to the overlapping of muscles, can't exactly identify the muscle despite it "looking correct"
imagine the thoughts your future audience will have, the majority of which will be artistic laymen: it will almost certainly look correct to them even if it's not attaching exactly where it needs.
don't sacrifice subtlety of detail and gesture in the name of academic accuracy. you'll spend too long overthinking a pose and drawing ugly details that don't serve the whole, especially when drawing women that are served far better by less detail that accentuates soft/delicate skin.
even the man in your example has defined, abstracted muscle groups, but the hatching to define them is used sparingly. it's used even less on the woman.
