ANATOMY OF A MUSCLE

Discover what your muscles are made of

Muscles are made up of bundles of fibres contained within protective sheaths called fascia, which are themselves bundled together.

The biggest bundle is the muscle itself. The next biggest bundles are the fascicles, which contain the long, single-celled muscle fibres. Muscle fibres are then divided into myofibrils, which are divided again into bundles of myofilaments, made up from chains of sarcomeres.

1. Tendon

Strong, connective tissue that connects muscle to bone.

2. Epimysium

A layer of connective tissue that encases the entire muscle.

3. Endomysium

Connective tissue that covers the muscle fibres and also contains capillaries (tiny blood vessels) and nerves.

4. Perimysium

A layer of connective tissue that bundles together between ten and several hundred individual muscle fibres to create fascicles.

5. Fascicle

A bundle of individual muscle fibres.

6. Myofilaments

Smallest fibre bundles, made up of sarcomeres, the basic unit of a muscle.

6. Muscle fibre

Individual muscle fibres come in two main types: type 1 or slow-twitch, which are suited to endurance because they are slow to fatigue; and type 2 or fast-twitch, which are quick to fatigue and are therefore better suited to fast, explosive movements.

7. Blood vessel

Part of the body’s circulatory system, blood vessels come in three types: arteries, which are responsible for transporting oxygenated blood away from the heart to the organs and tissues; capillaries, which enable the exchange of nutrients and waste products between the blood and the tissues; and veins, which transport deoxygenated blood from the capillaries back to the heart.