Madonna's Anatomy: The 50-year-old's arms looked more sinewy than ever

If ever she tires of showbiz, a new career clearly awaits Madonna.

She could pose for medical students keen to learn about the muscular system.

Her once hefty arms have now lost every trace of fat, causing every vein and sinew to stand out in stark relief.

Madonna, 50, was pictured as she left a restaurant on Sunday night and returned to her London home.

Perhaps she needs to rethink her fitness sessions with personal trainer Tracy Anderson, which involve gruelling two-hour workouts six days a week while drinking coconut water to keep energy levels high.

Miss Anderson is based in New York but flew to London to help the star prepare for her European tour.