The ornamental design for a medical apparatus, substantially as shown and described.
FIG. 1 is a front perspective view of the medical apparatus;
FIG. 2 is a front view of the medical apparatus;
FIG. 3 is a rear view of the medical apparatus;
FIG. 4 is a right side view of the medical apparatus;
FIG. 5 is a left side view of the medical apparatus;
FIG. 6 is a top view of the medical apparatus; and,
FIG. 7 is a bottom view of the medical apparatus.
The broken lines showing portions of the medial apparatus are included for the purpose of illustrating non-claimed subject matter and form no part of the claimed design. Dash-dot-dash lines show boundaries of claimed subject matter.