The ornamental design for a massagehead of massage apparatus, as shown and described.
FIG. 1 is a front perspective view of a massage head of massage apparatus showing my new design;
FIG. 2 is a back elevational view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a right-side elevational view thereof;
FIG. 5 is a left-side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines shown in the figures are for the purpose of illustrating portions of the massage head of massage apparatus, which form no part of the claimed design.