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Rotator cuff
Four muscles running from the shoulder blade to the top of the arm bone, holding the ball centred in a very shallow socket.
Latin name: Musculi supraspinatus, infraspinatus, teres minor, subscapularis. In plain English, the four small muscles that hold the shoulder in its socket. It is filed here under shoulder and shoulder blade.
Reference information, not a diagnosis. Where a symptom is described below, it is there so you can describe your own more precisely to a clinician — not so you can name what you have.
Where it is
The shoulder socket is shallow — the head of the humerus sits against it rather than in it, the way a golf ball sits on a tee. Three of the four cuff muscles run from the back of the shoulder blade over the top and back of the joint to the greater tubercle on the outside of the arm bone; the fourth, subscapularis, runs across the front surface of the shoulder blade, between it and the ribs, to the lesser tubercle. Their tendons blend with the joint capsule, so the cuff is as much a reinforcement of the capsule as it is four separate muscles.
Supraspinatus has the least room. Its tendon passes through a narrow gap between the head of the humerus below and the acromion and coracoacromial ligament above, and that gap contains a bursa as well. Anything that reduces the space — a bone spur, a swollen bursa, a thickened tendon, or simply working with the arm above shoulder height for hours — is felt there first.
| Feature | Detail |
|---|---|
| Supraspinatus | Supraspinous fossa of the scapula to the upper facet of the greater tubercle; suprascapular nerve (C5-C6); starts abduction |
| Infraspinatus | Infraspinous fossa to the middle facet of the greater tubercle; suprascapular nerve (C5-C6); external rotation |
| Teres minor | Lateral border of the scapula to the lower facet of the greater tubercle; axillary nerve (C5-C6); external rotation |
| Subscapularis | Subscapular fossa, on the front of the shoulder blade, to the lesser tubercle; upper and lower subscapular nerves (C5-C7); internal rotation |
| Main actions | Holding the head of the humerus centred in the socket; rotation of the arm inward and outward, and initiation of abduction |
What it does
The cuff's main job is not movement, it is centring. When the big muscles pull on the arm, the cuff pulls the head of the humerus down and into the socket so it rotates in place instead of riding upward. Take that away and the deltoid alone tends to shove the arm bone up under the acromion, which is why a badly torn cuff produces a shoulder that shrugs instead of lifting.
Their individual actions matter for testing. Supraspinatus starts abduction, so weakness shows up in the first part of lifting the arm sideways. Infraspinatus and teres minor rotate the arm outward, tested with the elbow at the side. Subscapularis rotates it inward, the one movement people never train and the one that is hardest to test at home. Clinicians use those directions to separate which tendon is involved, which is a good reason to get a stubborn shoulder looked at rather than guess.
Exercises that load it
| Exercise | Category | Muscles the exercise library lists |
|---|---|---|
| Overhead press | Strength | Shoulders, triceps, core |
| Bench press | Strength | Chest, triceps, front shoulder |
| Pull-ups | Strength | Lats, biceps, mid-back, grip |
| Bent-over row | Strength | Mid-back, lats, biceps |
| Swimming, freestyle | Cardio | Whole body, heart, lungs |
Every pressing and pulling movement loads the cuff whether you plan it or not, because holding the joint together is the price of moving the arm under load. Direct work is deliberately light: external and internal rotation with a band or a small weight, elbow tucked at the side, for higher repetitions. The cuff muscles are small and their tendons are the vulnerable part, so heavy loading of the rotations rarely helps and frequently irritates.
How it is lengthened
Cuff tightness is usually posterior: the back of the capsule and infraspinatus lose length in people who throw or serve on one side. A cross-body stretch with the shoulder blade held still, or a side-lying sleeper stretch taken gently, addresses that. The front of the shoulder generally does not need stretching — it needs the shoulder blade to move properly, which is a strength problem rather than a length problem.
When it goes wrong
| Problem | What it typically feels like | Usual setting |
|---|---|---|
| Rotator cuff related shoulder pain | A dull ache on the outside of the upper arm, worse reaching overhead or lying on that side at night | Repeated overhead work or sport, or a period of unaccustomed loading |
| Cuff tear | Weakness rather than only pain — the arm cannot be held out to the side, or drops when lowered slowly | A fall onto the arm, or gradual degenerative change with age |
| Subacromial bursitis | A painful arc partway through raising the arm, easier at the very top and the very bottom | Overhead sport or work, often with a sudden increase in volume |
A shoulder that cannot be actively lifted after a fall, or one that stays weak rather than merely sore, needs an in-person examination. So does night pain that stops you sleeping for weeks. Do not self-diagnose a tear from an internet test.
Nothing on this page is a treatment plan. If a problem is limiting what you do, is not improving, or is getting worse, the right next step is an assessment by a doctor or a physiotherapist who can examine you.
Sources: descriptive anatomy from Gray's Anatomy of the Human Body, 20th US edition (1918), which is in the public domain; Latin names follow Terminologia Anatomica, published by the Federative International Programme for Anatomical Terminology. Nerve root levels are the conventional ranges taught from those sources and vary between individuals and between textbooks. Exercise cross-links use the TempoLife exercise library. Checked 2026-09-06.
Frequently asked questions
Which rotator cuff muscle is injured most often?
Supraspinatus is the one most commonly involved, because its tendon passes through the narrowest space in the shoulder and it is loaded every time the arm goes out to the side.
Should I stretch or strengthen a sore rotator cuff?
Neither is automatically right, which is why this page will not prescribe. In general, cuff problems respond better to graded loading than to stretching, but a shoulder that has been painful for weeks needs someone to examine it rather than a rule of thumb from a website.
Is the rotator cuff the same as the shoulder joint?
No. The cuff is the four muscles and their tendons; the glenohumeral joint is the ball, socket, labrum and capsule they surround. Both can hurt in the same place, which is one reason shoulder pain is hard to self-diagnose.
Nearby in this reference
Deltoid
The cap of the shoulder
Trapezius
The big diamond across the upper back and neck
Rhomboids
The straps that pull the shoulder blades together
Serratus anterior
The finger-like muscle on the ribs that pins the shoulder blade down
Biceps brachii
The two-headed muscle at the front of the upper arm
Triceps brachii
The three-headed muscle at the back of the upper arm
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