Recap: Last time we went over the common mistakes of drawing breasts. Air-Balloon Boobs, Squished Boobs, misconceptions about nipple size, and of course Anti-gravity Boobs. If you’re a teenage boy, you’re probably wondering, “Stan, what’s wrong with this?!” This is fine for some genres of art, but if you’re drawing realistic women, this won’t happen.

Ok, let’s learn how to draw breasts correctly.

Form

Let’s remember our bones and muscles for a second. The forms you see near the armpit and clavicles are from the pectoralis major muscle.

This muscle appears and acts the same way on a female as it does on a male. Be sure to study the lesson on pecs.

Of course, on females, there’s an additional mass that sits on the lower part of the pecs. The transition from muscle to fatty tissue is soft and gradual. Notice that the breast mass flows with the pectoralis major into the armpit.

Remember that the ribcage is rounded, so the breasts are naturally aimed outwards at roughly a 45 degree angle. This means that the nipples are not dead-center. Instead, they sit closer to the outside edge of the breasts.

From the side view, we can see the upward facing plane of the chest. After the upwards-facing plane (orange) is a downwards-facing plane (blue). For small and perky breasts, there’s a gradual angle back into the ribcage. For larger breasts, the weight pushes them down and then they swoop back up to the infra-mammary fold.

Motion

The breasts will react to movements of the body. So, they will look different in different poses. When lying on the back, the breasts roll off the sides of the ribcage. This means they’re flatter and more distant from each other.

When bending over, the breasts will hang off the chest.

The breasts follow the motion of the shoulders. When the arms go up, the breasts go up, and the inframammary fold softens. When one arm goes up, the breast on that side will go up. The same applies for adduction and abduction of the arm. This causes the breasts to compress and stretch.

When hanging upside-down, the breasts will roll up the chest, in the same way they roll to the sides when the figure is lying on her back.

When lying flat on the stomach, the breasts are squeezed between the chest and the ground plane.