The subscapularis (rotator cuff)
Subscapularis · musculus subscapularis
The biggest rotator cuff muscle, on the front of the shoulder blade, that turns the arm inwards.
What it does
The subscapularis fills the front surface of the shoulder blade, lying between it and the ribs. It rotates the arm inwards, as when you tuck your hand behind your back, and stops the head of the humerus slipping forward out of the socket.
Surprising fact
It is the largest and strongest of the four rotator cuff muscles, yet it is hidden against the ribs, so you can't see or easily feel it.
Why it matters
Because it guards the front of the shoulder, it is often damaged when a shoulder dislocates forwards, which is by far the most common direction.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.