Draw a simple arm outline with the shoulder, upper arm, elbow, forearm, and wrist
Mark the biceps area on the front of the upper arm
Mark the triceps area on the back of the upper arm
Add the deltoid shape at the shoulder
Sketch the forearm muscles as long tapered forms from elbow to wrist
Use curved lines to show muscle volume and direction
Define the biceps with a rounded outer contour
Define the triceps with a broader rear contour
Add the brachialis between the biceps and triceps near the elbow
Indicate the elbow joint with a bony point and crease lines
Refine the muscle separations with light contour lines
Adjust proportions so the upper arm is thicker than the forearm
Add shading to show form and muscle depth
Smooth the outlines and erase construction lines