Muscles A–Z — Every Major Muscle, Explained

There are more than 600 named skeletal muscles. This reference covers 180 of the major ones that students, clinicians and curious readers look up most often — every large mover of the limbs and trunk, the muscles of the face and chewing, the breathing muscles and the small muscles of the hands and feet.

They are the two ends of a muscle. The origin is the attachment that usually stays fixed — often the end nearer the trunk — and the insertion is the attachment that usually moves, often on the bone being pulled. When a muscle contracts, it draws the insertion toward the origin. In the limbs the roles can reverse (for example when you pull yourself up toward a fixed arm), but the origin and insertion names stay the same.

Gluteus maximus, the big buttock muscle you use to rise from a chair and climb stairs, is the largest by volume. The longest is sartorius, a strap that runs diagonally across the front of the thigh from hip to knee. The strongest by absolute force is often said to be the masseter, the jaw muscle, because of the mechanical advantage of the jaw.

Every muscle is switched on by a motor nerve. Knowing which nerve supplies a muscle is how clinicians test it: if a nerve is injured, the muscles it supplies weaken in a recognisable pattern. Each page in this guide lists the muscle’s nerve and the spinal levels it comes from, in brackets — for example, femoral nerve (L2–L4).

A few entries describe named groups whose members are also listed individually — for example the rotator cuff, the quadriceps and the hamstrings. The group page explains what the muscles do together; follow the links to each member for its own origin, insertion and nerve.

Illustrations make attachments much easier to remember. Our recommended anatomy art collection — linked from the hub page — gathers muscle and anatomy artwork in one place, and the site’s anatomy videos show many of these muscles in context.