Number 6 — The Shape of Every Muscle

The number 6 is the muscle. A round head tapering to a pointed tail — exactly the shape of a muscle fiber. Every major muscle in the body is a variation of the elongated 6.

KEY CONCEPTS

Every major muscle is an elongated 6 — round belly, pointed tendon ends
The deltoid (shoulder cap) is the first large 6 in the arm sequence
The bicep is a 6 on the front of the upper arm
The tricep is a larger 6 (three heads) on the back of the upper arm
The forearm contains multiple small 6s packed together
Muscles squish and interlock against each other like puzzle pieces

Every muscle has a rounded belly (the fullest, thickest part in the middle) and two tapered ends (the tendons, which attach to bone). The number 6 captures this perfectly: the round loop at the top is the belly, the descending tail is the tapered tendon end. Draw 6s and you are drawing muscles — it really is that simple.

The deltoid is the triangular muscle capping the shoulder. It has three sections: front (anterior), middle, and rear (posterior). The middle deltoid creates the widest point of the shoulder. In heroic figures, the deltoid is drawn as a dramatic rounded mass sitting on top of the arm, like a round shoulderpad — that exaggeration communicates shoulder power at a glance.

The tricep (back of the upper arm) is actually larger than the bicep in most people — but beginners always focus on the bicep. For heroic drawing, the tricep's horseshoe shape seen from behind is one of the most powerful arm silhouettes you can draw. Learn to love the back of the arm as much as the front.

TRY THIS — 10 MINUTESDraw five 6-shapes of different sizes on your page. Now arrange three of them to form an arm: large 6 (deltoid) at the top, medium 6 (bicep) below and in front, large 6 (tricep, horseshoe) behind and below. Connect them at the elbow joint (a zero circle). You can see exactly how muscles stack and connect along the arm from shoulder to elbow.