Drawing a lung starts with understanding its basic shape: a half-cone, wider at the bottom and narrowing to a blunt point at the top. The two lungs are not identical, and getting the differences right is what separates a rough sketch from an accurate one. Whether you’re working on a biology assignment, a medical illustration, or an art project, this guide walks through the anatomy step by step so your drawing looks realistic.
Start With the Overall Shape
Think of each lung as half of a cone sliced vertically. The outer surface is rounded and convex, following the curve of the rib cage, while the inner (medial) surface is flatter. The top of each lung, called the apex, is a blunt rounded point that actually extends above the first rib, reaching up toward the base of the neck. The bottom, or base, is concave and cups downward like a shallow bowl because it rests on the dome of the diaphragm.
Begin by lightly sketching two tall, rounded triangles side by side with a gap between them for the trachea and heart. Make the right lung slightly wider and shorter, and the left lung slightly narrower and taller. The left lung is smaller overall because the heart takes up space on that side. Keep the outer edges gently curved, not straight, and let the bottom edges scoop inward to suggest the diaphragm beneath.
The Right Lung Has Three Lobes
The right lung is divided into three sections: the superior lobe at the top, the middle lobe in the center, and the inferior lobe at the bottom. Two lines (fissures) separate them. Draw a roughly horizontal line about one-third of the way down the lung to create the boundary between the superior and middle lobes. Then draw a diagonal line running from the back of the lung downward and forward to separate the middle lobe from the inferior lobe. This diagonal line also separates the superior lobe from the inferior lobe along the back of the lung, so it forms a long sweeping curve from upper-back to lower-front.
These fissure lines don’t need to be perfectly straight. In real lungs they follow gentle curves, so a slightly arced line looks more natural than a ruler-straight one.
The Left Lung Has Two Lobes and a Notch
The left lung only has two lobes: superior and inferior, separated by a single diagonal fissure running from upper-back to lower-front, similar to the oblique fissure on the right side.
The key feature that makes the left lung look distinct is the cardiac notch. This is a concave indentation on the inner front edge, roughly at the level of the fourth rib. Instead of drawing a smooth curve along the left lung’s front border, scoop the line inward to create a crescent-shaped cutout where the heart sits. Just below this notch, the lung tissue extends forward again as a small tongue-like projection called the lingula. Drawing this little tab of tissue jutting out beneath the notch immediately signals to any viewer that they’re looking at the left lung.
Adding the Trachea and Bronchi
Above the lungs, draw the trachea as a straight vertical tube, roughly centered. It’s about 1.8 centimeters wide in an adult, so relative to the lungs it should look like a thick drinking straw. Add horizontal rings across it to represent the cartilage bands that keep it open.
At the bottom of the trachea, split it into two branches, one angling into each lung. The right branch is wider and angles more steeply downward, while the left branch is narrower and angles more horizontally. This asymmetry matters for anatomical accuracy. Each main branch then splits again inside the lung into smaller and smaller tubes. A useful rule of thumb: each time a branch divides, the two “daughter” branches are unequal. The larger branch is roughly 80% the diameter of its parent, and the smaller branch is roughly 76% the diameter of the larger one. You don’t need to measure this precisely, but making each generation of branches noticeably thinner and slightly uneven creates a realistic tree-like pattern.
Draw three to four generations of branching inside each lung, getting progressively thinner and shorter. Let them fan out to fill the lung’s interior, like the branches of an upside-down tree.
Drawing the Base and Diaphragm
The bottom of each lung should not be flat. The diaphragm beneath it is a double-domed muscle, higher on the right side (because the liver sits underneath) and slightly lower on the left. Each dome curves upward into the lung’s base, so the lung’s bottom surface is concave, cupping over the diaphragm like an upside-down bowl.
If you’re drawing the lungs within a torso, sketch the diaphragm as a broad curved line beneath both lungs, peaking higher under the right lung. The lungs sit on this curve, and their lower edges should follow it rather than ending in a horizontal line.
Surface Details and Texture
Real lungs have a smooth, glistening outer membrane called the visceral pleura, which gives them a shiny, slightly wet appearance. For a simple diagram, the surface can stay clean. For a more realistic illustration, try these approaches:
- Light shading: Add a gradient from darker at the edges to lighter where a light source would hit, giving the lung a sense of rounded volume.
- Faint polygonal pattern: The lung surface has a subtle mosaic of small polygonal shapes visible through the pleura. Lightly sketching irregular hexagons or pentagons across the surface suggests this lobular pattern without overwhelming the drawing.
- Color: Healthy lungs are a pale pink with a slightly spongy look. If you’re using color, a soft pink-gray works well, with the fissure lines in a slightly darker shade.
Adding Alveoli for a Zoom-In Detail
If your drawing includes a magnified inset showing the lung’s interior, you’ll want to illustrate alveoli. These are tiny air sacs clustered at the ends of the smallest airways, like bunches of grapes at the tips of a vine. The lungs contain about 150 million of them. Draw them as small, rounded, bubble-like circles grouped in clusters of five to eight, connected to a tiny airway tube. Wrap a fine mesh of lines around each cluster to represent the blood vessels (capillaries) that cover every alveolus. This grape-cluster-with-netting look is the standard way alveoli appear in medical illustrations.
Alveoli are elastic and slightly irregular in shape, so avoid drawing perfect circles. Slightly varied, organic-looking ovals packed together will read as more accurate.
Medial View and the Hilum
If you’re drawing the inner surface of a lung (the side facing the other lung), you need to include the hilum. This is the area on the medial surface where the main bronchus, blood vessels, and nerves enter the lung. Draw it as an oval or triangular depression roughly in the center of the inner face. From this spot, sketch the bronchus entering the lung along with one or two large vessels (the pulmonary artery bringing blood in and pulmonary veins carrying it out). The bronchus is typically positioned toward the back, with the artery above it and the veins below and in front.
On the left lung, the cardiac impression is a large concave area on the medial surface below and in front of the hilum, where the heart presses against the lung. Draw this as a broad, shallow indentation taking up much of the lower medial surface.
Proportions to Check Before Finishing
Before finalizing your drawing, verify a few proportions. The thick back border of each lung spans from roughly the level of the seventh neck vertebra down to the tenth thoracic vertebra, giving the lung considerable height. The apex rises above the first rib. The right lung should look visibly wider but slightly shorter than the left. The trachea should split into its two branches roughly at the center of the chest, behind the upper part of the breastbone.
If you’re drawing both lungs from the front, keep a visible gap between them (the mediastinum) where the heart, trachea, and major blood vessels sit. This space is wider at the bottom, especially on the left side where the cardiac notch opens up. Making this gap too narrow is one of the most common mistakes, as it leaves no room for the heart and makes the drawing look anatomically off.