Maybe, alpha strike is right, maybe, he is wrong.
I don't think that this character is impossible within the laws of nature and human anatomy.
I think that it just contradicts certain expectations and feelings of harmony. (Yes, harmony within the proportions of a monster!
)
An orc is expected to be strong and slow, more like a bear not like a fox.
Small ankles are a sign of being fast and light, not of carrying a big weight and bulk of muscles.
Your orc symbolizes a mixture of fast and strong and dump, it is sort of undecided what sort of character he is. He has big muscles but hands that are so small that they crash when he uses the whole power of his arm muscles.
Then the part where alpha strike made definitely a good point:
it is a humanoid character, that means one expects that his muscles fit more or less with the task and sit and proportions of the muscles of a human body.
It is good to imagine (and draw) a mammal creature as a construction of sticks (the bones) and threads(the muscles and sinews) to get a more harmonic anatomy.