The infraspinatus (rotator cuff)

What it does

The infraspinatus covers most of the back of the shoulder blade below its ridge. It rotates your arm outwards, as when you swing a tennis racket back, and helps keep the ball of the shoulder centred in its socket.

Why it matters

Throwers and swimmers rely on it to slow the arm down at the end of a throw or stroke, so it is often the source of shoulder soreness in those sports.

Nearby

• The supraspinatus (rotator cuff)
• The teres minor (rotator cuff)
• The subscapularis (rotator cuff)
• The shoulder blade

Read more

• Infraspinatus — Wikipedia