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Learn to draw the humerus, radius, ulna, and hand bones in proportion using a clear bone-by-bone method, with checks, practice tasks, and a marking rubric.
Drawing an arm skeleton is easier when you build it bone by bone instead of copying a finished outline. This lesson treats the arm as four connected units: the humerus in the upper arm, the radius and ulna in the forearm, and the hand bones grouped as carpals, metacarpals, and phalanges. You will use a simple convention: every bone is drawn as a long shape with two ends, and every joint is marked with a small gap so bones do not merge. Proportions are checked with a ruler or by counting grid squares, not by eye alone. The method works for any arm position because you first place the joint centres, then wrap each bone around them. All measurements below are hypothetical examples chosen for practice; measure your own paper and tools if you need exact values.
Practice materials: Printable downloads are not available for this lesson yet. Use the instructions and four exercises below.
Use the stated measurements and conventions for each exercise.
Start with five points: shoulder, elbow, wrist, and two knuckle landmarks for the thumb side and little-finger side of the hand. These points control the whole drawing. If the elbow sits halfway between shoulder and wrist, the forearm and upper arm read as balanced. Mark each point lightly and label it in pencil so you can erase later.
Use a consistent unit. For example, if the shoulder-to-elbow distance is 6 grid squares, make the elbow-to-wrist distance about 5 squares. These are hypothetical practice values, not anatomy standards. The important check is that your own two distances stay in the same ratio when you redraw the arm at a different size.
The humerus is the single upper-arm bone. Draw it as a long shaft that narrows slightly in the middle and widens at the shoulder and elbow ends. Keep the shaft centred on the shoulder-to-elbow line. The shoulder end is rounder and broader; the elbow end is flatter and wider side to side.
Leave a small gap at each joint. A gap of about one pencil width is enough at this scale. The gap is a drawing convention that shows where one bone ends and the next begins; it is not a measurement of real joint space.
The forearm has two bones. The ulna runs on the little-finger side and is slightly thicker at the elbow end. The radius runs on the thumb side and is slightly thicker at the wrist end. Draw both as long, slightly curved shafts between the elbow gap and the wrist gap.
Keep a clear space between the two bones along most of the forearm. Near the wrist, the radius end is broader; near the elbow, the ulna end is broader. This opposite widening is the main visual cue that helps viewers read the forearm correctly.
The hand is drawn as three groups: a cluster of small wrist bones near the wrist gap, a row of five long palm bones, and the finger bones beyond the knuckle landmarks. Do not try to draw every small wrist bone separately at first; draw the cluster as a rounded block divided by two or three light lines.
For the palm bones, draw five short shafts fanning from the wrist cluster to the knuckle line. The thumb-side palm bone sits lower and angles outward. Beyond the knuckles, draw finger bones as two or three short segments per finger, with small gaps at each joint. The thumb has fewer segments and angles away from the other fingers.
A practice grid uses 1 square = 1 unit. The shoulder is at (2, 8), the elbow at (2, 2), and the wrist at (7, 2). Draw the arm skeleton bone by bone and state the upper-arm and forearm lengths in units.
Upper arm length = 8 - 2 = 6 units. Forearm length = 7 - 2 = 5 units. Draw the humerus from (2,8) to (2,2) with a gap at the elbow, then draw the ulna and radius from the elbow gap to the wrist gap at (7,2), with the ulna on the little-finger side and the radius on the thumb side. Add the wrist cluster, five palm bones, and finger segments beyond the knuckle line. The ratio of upper arm to forearm is 6:5.
On a grid where 1 square = 1 unit, the shoulder is at (1, 9), the elbow at (1, 3), and the wrist at (6, 3). State the upper-arm and forearm lengths and the ratio.
Upper arm = 6 units; forearm = 5 units; ratio 6:5.
Why: Subtract the y-coordinates for the upper arm: 9 - 3 = 6. Subtract the x-coordinates for the forearm: 6 - 1 = 5. The ratio is 6 to 5.
Check: Re-measure both distances with the same grid unit and confirm the ratio matches 6:5.
A draft has an upper arm of 8 units and a forearm of 4 units. The learner wants the forearm to follow the lesson's 6:5 practice ratio. What forearm length should they use, and by how much must they change the draft?
Forearm should be about 6.7 units, so lengthen it by about 2.7 units.
Why: Set up 8 / forearm = 6 / 5. Cross-multiply: 6 x forearm = 40, so forearm = 40 / 6, which is about 6.7. The change is 6.7 - 4 = 2.7 units.
Check: Divide the new upper arm by the new forearm: 8 / 6.7 is about 1.2, matching 6 / 5 = 1.2.
Describe where to place the ulna and radius in a forearm drawn from an elbow gap to a wrist gap, and state one visible difference between their ends.
Place the ulna on the little-finger side and the radius on the thumb side. The ulna is wider at the elbow end; the radius is wider at the wrist end.
Why: The two forearm bones run side by side between the elbow and wrist gaps. Their opposite widening is the main cue that distinguishes them in a drawing.
Check: Confirm the two bones are separate along the forearm and that each has its wider end at the correct joint.
A hand drawing shows a wrist cluster, five palm bones, and finger segments, but the thumb group points in the same direction as the other fingers. State the correction and one check.
Angle the thumb group outward from the other fingers and keep a joint gap at its base. Check that the thumb-side palm bone sits lower and angles away from the little-finger side.
Why: The thumb is drawn as a separate group with fewer segments and an outward angle. If it parallels the other fingers, the hand reads as a block rather than a grouped structure.
Check: Trace from the wrist cluster to the thumb tip and confirm the path leaves the palm-bone row at a different angle from the other fingers.
No. At this scale, a rounded wrist cluster with two or three dividing lines is enough. The lesson focuses on bone-by-bone construction, not clinical detail.
Use about one pencil width at a practice scale where the upper arm is 6 grid squares. This is a drawing convention, not a real joint measurement.
Yes. Place the joint centres first, then wrap each bone around its two endpoints. The same bone-by-bone order works for straight or bent arms.
Check the wrist-to-knuckle distance against the elbow-to-wrist distance. If the hand is less than about half the forearm length in your draft, lengthen the palm-bone row slightly and redraw the finger segments.