Capturing Realism in Lip Drawing: Key Structures and Shading

I was curious about the undulation of the muscles around my lips during the sketching process, so I organized the relevant structures and how to draw them.
By mastering the "structural pivot point" of the mouth, you can make your lips naturally three-dimensional and full of character.

Why is it advisable to understand the structure of the mouth?

• The mouth is one of the centerpieces of facial expressions and changes shape according to emotions

• The lips themselves are three-dimensional, not just thin lines.

• Mastering the structural pivot point allows you to handle light and shadow and proportion with relative precision.

Main divisions of the mouth

Upper Lip

Includes lip bulb (center point), lip pier (small left and right arches), lip peak (high point of upper edge)

• Anatomically: major thickness of the red area of the upper lip.

• Scope:From the lip brim downward → until the lip crease。

• Upper Lip Function: Determines the volume and curvature of the upper lip.

• situated in Upper LipThe main area of the
• upper bound: Lip brim, connecting the upper part of the lip / mid-arches.

lit. lip and brim

• Anatomically: a small elevation between the "skin of the face" and the "redness of the lips".
• Function: A demarcation line that makes the lips jump out from the face in a three-dimensional way.

lips

• The "white shiny edge" where the skin meets the red lip.Make a full circle along the upper and lower lips.This includes the peak of the lip, the bead of the lip, and all the way to the ends of the sides.

• lower boundary: the red edge of the upper lip, bordering the lower lip.
• centerThere's a bulge. bead of lip 。

It can be interpreted as "the thickness of the upper lip red body".

Lower Lip

The center is the thickest and most anteriorly thrown, and the sides converge towards the corners of the mouth.

Compared to the upper lip, it is fuller, but it varies a bit, and is usually smoother and rounder, with the most protruding point just below the lip bulge.

corner of the mouth

A turning point where the lips converge, dark spots and wrinkles are common.

• Function: Determines the length of the cleft and the direction of expression.
• Definition:The point where the red border between the upper and lower lips meets.The corners of the mouth are also known as the "corners of the mouth".

• Appearance: The position of a surface visible on the face.

Manzhong District

Skin between the base of the nose and the red border of the upper lip, affecting the arch of the upper lip

Anatomical position

• situated in nasal columella Below that, it extends to Upper Lip The center.
• Its left and right borders are the two borders that are formed by the two alveolar ridge constitute

alveolar ridge: Two slight bulging lines extending down from the lower part of the nasal columella.

• The center is Human Warrant 。
• lower end → center of upper lip bead of lip 。

頦唇溝

Shadow of lower lip and chin demarcation

The "fulcrum" of the mouth structure

The key to lip contouring is not in the stroke, but in mastering the following pivots:

bead of lip

The small paraboloid in the center of the upper lip is the brightest point of illumination.

Worm Shaft

• Location:about Lateral corner of the mouth 3-5 mmThe mouth is more "deep and lateral" than the corners of the mouth.

• definition: A subcutaneous area located slightly lateral to the corner of the mouth. Muscle Fiber Junction。

Deep: Yes Orbicularis oculi, smile muscles, levator ani, descenser ani, cheek muscles It is a "pivot point" where several muscle fibers are interwoven under the skin.

Corner of the mouth,蝸Summary of axial differences

• Oral arguments = superficial structures(You see the corners of the mouth pointing)
• Worm axis = deep muscle meeting point(hidden under the skin at the outer corners of the mouth).
• They are located close together but don't exactly overlap:
• Mouth corners in front and outside view.
• The snail shaft is behind and under the skin.

Jogging Tracks

Turning line between lower lip and chin

Jogging BoardIt is the "natural concave line between the lower lip and the chin", which is defined by thePoor tension at the junction of the orbicularis oculi and chin muscles.Formation.
It allows the mouth and chin to be separated, creating a three-dimensional turn, and is an important basis for realizing the structure of the mouth in portraits.

Jogging TracksHow?

Power junction of the lower lip and chin muscles

• The lower lip is mainly composed oforbicularis oculi muscle (anatomy)與Lower lip and incisor musclesTraction
• The chin is made up ofjogging boardLeading (pushing upward). → The two sets of muscles meet and tension is directed in opposite directions, creating an "indentation" at the junction.

Differential thickness of the fat layer

Thicker fat in the lower lip area and thinner chin area → a visual turnaround occurs.

• positively: look for the bottom of the lower lip (the lower lip pad) → look for the first horizontal curve towards the chin, which is the chin-lip groove.

• side: After the lips are protruding, there is an area that turns backward into the chin's concavity → that turn is the chin-lip cleft.

nasolabial communication

It slides from the side of the nose to just below the outer corners of the mouth, and is the main shadowing edge of the outer frame of the upper lip.

From the outside of the nose → downward diagonally → to the corner of the mouth

Lower Lip Pads / Cheek Pads

An important source of volume that supports the thickness of the lips

Lips Lighting Performance

We can also divide the upper and lower lips into inner and outer layers, with the outer layer being the lighted side and the inner layer being the part that turns into the dark side. The boundary line between the inner and outer layers can be seen in the small figure in the center, a line that follows the undulation of the lip structure.

upper lip

Facing downward → mostly in shadow, only the beads of the lips are brightened with lip piers

It is easier to see the turn of the face more clearly by observing the turn of the shape through the angular lips.

Transitions affect the shape and intensity of shadows.

lower lip：

Forward facing → Center throws out the most light, lower edge has a bright band due to the chin return.

Wet & Dry Junction

The outer border inside the lips creates a fine line of shine and moisturizing sensation.

• Definition: The boundary between the inner mucous membranes of the mouth (wet zone) and the outer lipstick (dry zone).
• Position: When the mouth is gently closedUpper and Lower Lip Medial Contact Lines。
• Function: Here the tissues have different characteristics, the dry area is like the skin and the wet area is like the mucous membrane.

corner of the mouth

The deepest depressions and dark spots are concentrated

Jogging Board

it isBetween the lower lip and chin (chin)The indentation (the projection of the lower lip) of the mouth gives a natural demarcation between the mouth and the chin.

Located:Below the lower lip node (the most convex point of the lower lip)The chin is located between the chin and the most prominent point of the chin.

Appearance: a soft horizontal concave line on both the front and side view.

• 在Shut up and relax.This is most obvious when you are in the middle of a journey;
• Laughing or talkingIn the case of the chin, it will change with the activity of the orbicularis oculi and chin muscles.

Overall structure around the mouth

• core muscle: orbicularis oculi
• Peripheral synergistic muscleLifting upper lip, lower lip, chin, cheek, and corner of the mouth muscles.
• Scope of action: Between the base of the nose and the chin chin, extending horizontally to the corners of the mouth on both sides.
• functionality: Responsible for all mouth movements such as opening, closing, smiling, mouthing, pronouncing, etc.

👉 Think of it as "an oval ring of muscle", with the peripheral muscles acting as the strings that pull the rubber band around the ring.

For a more detailed understanding of the undulation and position of the muscles around the mouth, check out this article. Facial Muscle Focus Organizer

How do you paint your lips?

1. Simplify the shape of the lips and determine the proportions.

We have simplified the shape of the beads and lips into circles and ovals.

Pay attention to the size relationship between each other and draw the contours of the upper and lower lips, making sure that the center lines of the lips are aligned.

After the shape is completed, details such as the undulations on the lips are refined, and finally shadows are added to show the three-dimensionality of the lips.

2. Muscle undulation lines

After drawing the lips, use a soft line to show the muscles around the lips.

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Suggested Exercises for the Mouth

• Block Grayscale Sketch: Separate the upper lip, lower lip, chin, and chin

• Light source illumination: the same mouth shape, respectively: top-down light, side light, bottom-up light, three versions

• Dynamic ObservationDrawing the Relax, Smile, Pout trio to understand how the muscles change the shape of the lips.

• Age Comparison: Red lips are plumped up in the young, but shrinking in the old, with more vertical lines.

Mouth Structure Summary

The mouth is not a simple line, but a three-dimensional structure made up of "pivots" and "blocks".
As long as you understand the key points of the lip bead, lip pier, corner of the mouth, and chin-lip groove, and observe the changes in the rhythm of light and shadow, you will be able to draw the lips with naturalness and thickness, making the character more realistic and expressive.

I hope this introduction can help you recognize and understand the knowledge of lips, if there are any subjects you want to see or painting methods you want to know, welcome to leave a message or private message me, I wish you a happy painting!

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