The gestures of these chief emotions are instinctual, the muscle interactions and actions are subconscious. In general, the facial muscles are delicate, finely in step and easily seen because they lie just below the skin.

The facial muscles not only portray moods and gestures they also exhibit sympathetic characteristics. For example, when we are threading a needle we often pucker our lips to "aid" the thread through the needle's eye.

All facial gestures involve the muscles and other regions of the mouth. Therefore, to comprehend the facial gestures we must first comprehend the mouth which is more than just the lips.

The mouth region reaches from the bottom of the nose to the Mentolabial Sulcus, i.e., the sulk-line of the chin. The mouth is a convex form and wraps around the muzzle of the face.

Drawing the mouth should always begin with the articulation of the Interstice, i.e., the horizontal line where the lower and upper lips meet. The lips wrap around the convex protuberance of the dental curve and the interstice roughly corresponds to the middle segment of the frontal, upper teeth.

Note that the Nodes in the corners of the mouth are lower than the center of the interstice, except in a smile when the facial muscles pull up the nodes.

The lips, or Labia, are put together with mucous membrane whose pinkness results from the blood capillaries lying just under the skin.

The top lip has three shapes. In the center is the Tubercle which is non-muscular and add to the 'V' form of the upper lip where it meets the bottom of the Philtrum. The Philtrum is the stretched, vertical furrow that extends from the bottom of the nose to the tubercle of the upper lip.

The philtrum, which means "love drop", is surrounded by ridges on each side. Practically every beginning artist overextends the philtrum, thus placing the mouth too low.

The other 2 parts of the top lip are 2, horizontal stretched shapes. The muscles here, however, are the observable ridges of the middle vertical fibers of the Orbicularis Oris whose activity results in the puckering up of the lips. The various facial muscles attaching to the corners of the mouth do the pulling and pushing.

The top lip is flatter than the bottom lip. It is a downward facing plane and generally appears darker than the bottom lip. There is a small up-plane on the vermillion border of the upper lip that quite often catches a gentle light. For most people, the top lip tucks into the nodes.

The bottom lip generally stops a bit short of the nodes. The bottom lip is heavier and fuller. It consists of two stretched shapes that give it a more squared-off look than the top lip.

A little below the vermilion border of the bottom lip is a raised edge that develops laterally and is more conspicuous at the corners.

The vermilion border of the bottom lip should not be drawn with a hard line, it has to be suggested more than drawn. Or else it will look like lipstick.

The bottom lip is an up-plane and will often catch a highlight. Like the top lip, the ridges of the middle vertical fibers of the orbicularis oris form the texture of the bottom lip.

The bottom of the mouth region is at the mentolabial. Forming at the lower edge of the lower lip's two stretched shapes are two columnar tubes that radiate diagonally downward. These are the Pillars of the Mouth. This is a down plane and thus will lie in shadow.

With this we end the complete description of the elements that make the mouth and ultimately the smile.