FIG. 1 is a top perspective view of a mounting arm in accordance with the present design;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a side thereof, the opposite side view being the same;
FIG. 4 is a top view thereof;
FIG. 5 is a rear view thereof; and,
FIG. 6 is a bottom view thereof.
The broken lines in the drawings illustrate portions of the mounting arm which forms no part of the claimed design. Any shading forms no part of the claimed design and is provided to illustrate contour only and is not an indication of texture, gloss, and the like.