Step 10: Draw the top part of the boxer's muzzle using a series of curved lines inside the initial circle. First draw a line that starts right under the nose, and then curves left and ends on the lower, left edge of the initial circle. Then draw a shorter line on the right side to complete the droopy top lip.
Now follow the basic path of the initial circle as you darken the line to create the right side of the boxer's muzzle. Draw a couple of long, curved lines with a diagonal orientation to the left of the dog's nose for the folds of skin. Add a couple of lines on the right side too for the folds of skin there.
Step 11: Add the bottom part of the muzzle by first drawing a curved line under the mouth on the right side. Then draw a few curved lines under the lip on the left for the first set of jowls. Draw a few more curved lines to connect to the right side of the muzzle. Stay within the shape of the initial circle. You can add a few more short lines to emphasize the boxer's loose skin.
Step 12: Use the triangles on the head as guides to draw the boxer's ears. Follow the basic path of the triangles but make the lines rounder as you darken them. Add a few quick, short strokes on the ear for the furry texture. Draw the visible part of the ear on the other side the same way.
Step 13: Use the main circle as a guide to draw the rest of the dog's head. Follow the basic path of the circle but make the top part flatter and the left side narrower. Darken the line on the left for the back of the head/top of the neck. Add a few quick, short strokes on the lower, left side of the circle to emphasize the boxer's jawline.
Step 14: Add a few more lines within the boxer's head for extra detail. Some lines above the eyes represent the wrinkly forehead, and some under the eye emphasize the fur. Draw a few diagonal rows on either side of the muzzle too.