Academics uses cognition and intellect to conjur up ideas. The arm is a way by which psychomotor skills can express these thoughts. Something can be written up on a paper, drawn on a board or even tactically conveyed via sign language. However you use your arms, know that the tips can serve as a means for pleasuring and people often "dream" about those moments. Its a moment in time.
For purposes of this photo, it portrays an art and just as any painting, it used what was available to capture the eye of the beholder, thus, it was manufactured and created resulting in the final product, the photograph.