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Structure
Intermediate
9 min read

Rotator cuff

Four short muscles link the shoulder blade to the upper arm and hold the head of the humerus against its socket. They orient the shoulder more than they move it.
3D scene
The rotator cuff in the deep plane
The scene moves beneath the surface muscles to show the four heads wrapped around the head of the humerus. Without the 3D, the idea fits in one sentence: the cuff forms a sleeve stretched between the shoulder blade and the top of the arm, and that sleeve keeps the bone from leaving its place while the deltoid lifts the arm.
Open in the explorer

Where the rotator cuff is

The cuff is not one muscle but a group of four, short and deep, all starting on the shoulder blade and all ending on the top of the humerus. Their tendons merge into a continuous sheet that wraps the joint like a cap — hence the name.
It is almost entirely hidden. The deltoid covers it from outside, the shoulder blade masks it from behind, and the only one of the four you can reach by palpation is infraspinatus, in the hollow below the spine of the scapula.

Origins

Each of the four occupies a distinct region of the shoulder blade.
  • Supraspinatus arises from the supraspinous fossa, above the spine of the scapula.
  • Infraspinatus arises from the infraspinous fossa, below that same spine.
  • Teres minor arises from the lateral border of the scapula, below infraspinatus.
  • Subscapularis arises from the front surface of the scapula, the one facing the ribs.

Insertion

The first three attach to the greater tubercle of the humerus, the outer prominence at the top of the arm. Subscapularis alone attaches to the lesser tubercle, which sits further forward. That split explains the division of roles: three muscles pull backwards, one pulls forwards.

Nerve supply and palpable landmarks

Supraspinatus and infraspinatus are supplied by the suprascapular nerve, teres minor by the axillary nerve, subscapularis by the subscapular nerves. All these branches come from the C5 and C6 roots. In practice only infraspinatus can be palpated, in the hollow below the spine of the scapula.

What the rotator cuff does

Its main job is not to produce movement but to make movement possible.
  • Centring the humeral head: all four pull the humerus towards the glenoid cavity and hold it there while the large muscles move the arm.
  • Lateral rotation: infraspinatus and teres minor turn the arm outwards.
  • Medial rotation: subscapularis turns the arm inwards.
  • Initiating abduction: supraspinatus starts the arm moving away from the body, before the deltoid takes over.
Joint centring
Actively holding one joint surface against another during movement. At the shoulder, the socket that receives the humerus is shallow: without muscles continuously drawing the bone back into it, the head would slide instead of pivoting.
dynamic stabilisation
This division of labour is what makes the shoulder both very mobile and vulnerable. The glenohumeral joint is the most mobile in the body because its socket is small relative to the head it receives; the trade-off is that it depends on its muscles to stay in place.
Certainty level · Established
The rotator cuff actively stabilises the glenohumeral joint during arm movement.
Descriptive anatomy and kinesiology describe the mechanism in converging terms: the four tendons blend with the joint capsule, and their line of action pulls the humeral head towards the centre of the glenoid. What remains debated is the exact share of each muscle at a given arm angle, which varies between measurement methods.
Standring S (2020) · Neumann DA (2016)

Seeing the cuff in movement

The rotator cuff in the deep plane

The scene moves beneath the surface muscles to show the four heads wrapped around the head of the humerus. Without the 3D, the idea fits in one sentence: the cuff forms a sleeve stretched between the shoulder blade and the top of the arm, and that sleeve keeps the bone from leaving its place while the deltoid lifts the arm.
Current step
Deep and medial muscles
Beneath the visible groups work muscles no silhouette shows. The rotator cuff holds the head of the humerus against the shoulder blade, serratus anterior keeps the shoulder blade flat on the ribcage, the iliopsoas links the lumbar spine to the femur, and the adductors fill the inner thigh. Deeper still, the diaphragm closes the trunk as a dome, inside the ribs. They orient and stabilise more than they move.
Scene description
A three-dimensional diagram of a standing human body, arms by the sides, built from simplified paper-coloured volumes. Twelve priority muscle groups are laid over this outline in terracotta: at the front, pectoralis major, the deltoid, biceps brachii, the abdominal wall and the quadriceps; at the back, the trapezius, latissimus dorsi, the erector spinae, triceps brachii, the glutes, the hamstrings and the calves. A simplified skeleton — skull, spine, ribcage, pelvis, humerus, femur and tibia — can be shown beneath the outline to reveal the bony levers these muscles pull on. Each group is selectable and opens its own reference page. This is a teaching diagram with stylised volumes, not an exact anatomical reconstruction.
Visible structures
  • Pectoralis major
    A thick sheet running from the clavicle, the sternum and the upper costal cartilages to the lateral lip of the bicipital groove of the humerus. It draws the arm towards the midline and forwards, and drives horizontal pushing.
  • Deltoids
    Three heads — anterior, lateral and posterior — running from the clavicle, the acromion and the spine of the scapula to the deltoid tuberosity of the humerus. Together they raise the arm; separately they carry it forwards, out to the side or backwards.
  • Biceps brachii
    Two heads arising from the scapula — the supraglenoid tubercle and the coracoid process — joining on the radial tuberosity. It flexes the elbow and supinates the forearm, and contributes to every pulling movement.
  • Abdominal wall
    Rectus abdominis, the external and internal obliques and transversus, running from the ribs and sternum to the pubis and iliac crest. They flex and rotate the trunk and, above all, stabilise the spine by regulating intra-abdominal pressure.
  • Quadriceps
    Four heads — rectus femoris, vastus lateralis, vastus medialis and vastus intermedius — joining through the quadriceps tendon onto the patella and then the tibial tuberosity. They extend the knee, and rectus femoris also flexes the hip.
  • Trapezius
    A diamond-shaped muscle spanning from the occiput and the cervical and thoracic spinous processes to the clavicle, the acromion and the spine of the scapula. Its upper, middle and lower portions elevate, retract and depress the scapula.
  • Latissimus dorsi
    A broad fan arising from the lower thoracic vertebrae, the thoracolumbar fascia, the iliac crest and the lowest ribs, converging on the bicipital groove of the humerus. It pulls the arm down and back, and drives vertical pulling.
  • Erector spinae
    Muscular columns — iliocostalis, longissimus and spinalis — running from the sacrum and iliac crest to the ribs, the vertebrae and the skull, on either side of the spinous processes. They extend the spine and control the trunk as it lowers.
  • Triceps brachii
    Three heads — long, lateral and medial — arising from the scapula and the back of the humerus and joining on the olecranon of the ulna. It extends the elbow, and its long head also assists shoulder extension.
  • Glutes
    Gluteus maximus, medius and minimus, arising from the iliac wing and the sacrum and inserting on the femur and the iliotibial tract. They extend, abduct and rotate the hip, and drive the pelvis upright in the hinge and the squat.
  • Hamstrings
    Biceps femoris, semitendinosus and semimembranosus, running from the ischial tuberosity to the tibia and fibula. They extend the hip and flex the knee, and control the trunk as it lowers in the hip hinge.
  • Calves
    The gastrocnemius and soleus, joining through the Achilles tendon onto the calcaneus. They plantarflex the ankle, and the gastrocnemius, which crosses the knee, also assists knee flexion.
  • Rotator cuff
    Four short muscles running from the shoulder blade to the top of the humerus. Their tendons merge into a sheet that holds the head of the bone against its socket while the deltoid moves the arm.
  • Serratus anterior
    A sheet hooked onto the upper ribs by triangular slips, passing under the shoulder blade and attaching to its inner border. It holds the blade against the ribcage and rotates it.
  • Iliopsoas
    The only muscle linking the lumbar spine directly to the femur. It descends from the vertebrae and the iliac fossa, curves around the rim of the pelvis and attaches to the lesser trochanter.
  • Hip adductors
    Five muscles running from the pubis to the back of the femur in overlapping layers. They draw the thigh towards the midline and control the pelvis in single-leg stance.
  • Forearm muscles
    Masses gathered near the elbow, continued by long tendons to the wrist and fingers. They drive the hand from a distance and carry grip strength.
  • Tibialis anterior
    A muscle pressed against the outer surface of the tibia, its tendon swinging towards the inside of the foot. It lifts the toes on every step and brakes the forefoot after heel strike.
  • Diaphragm
    A muscular dome running from the lower border of the ribs, the sternum and the lumbar vertebrae to a central tendon. As it contracts it descends, the chest gains volume and air enters: it is the engine of quiet breathing, and the ceiling of the abdominal cavity.
Guided steps
  • 1/5
    The front of the body. Pectoralis major covers the upper chest, the deltoid caps the shoulder, the biceps fills the front of the arm, the abdominal wall links the ribs to the pelvis, and the quadriceps fills the front of the thigh. Further out on the limbs, the forearm muscles drive the wrist and hand, and tibialis anterior lifts the foot.
  • 2/5
    The back of the body. The trapezius links the neck to the shoulder blades, the latissimus dorsi fans down to the pelvis, the erector spinae flank the spine, and the triceps fills the back of the arm. Glutes, hamstrings and calves form the posterior chain from hip to ankle.
  • 3/5
    Beneath the visible groups work muscles no silhouette shows. The rotator cuff holds the head of the humerus against the shoulder blade, serratus anterior keeps the shoulder blade flat on the ribcage, the iliopsoas links the lumbar spine to the femur, and the adductors fill the inner thigh. Deeper still, the diaphragm closes the trunk as a dome, inside the ribs. They orient and stabilise more than they move.
  • 4/5
    In a push, force starts at the ground, travels through the quadriceps and the abdominal wall, and then pectoralis major, the anterior deltoid and the triceps drive the load away from the trunk. The skeleton acts as the lever: no group works alone, and the quality of the movement comes from their sequencing.
  • 5/5
    In a pull, the latissimus dorsi and trapezius bring the arm and shoulder blade towards the trunk while the biceps flexes the elbow. Glutes, hamstrings and erector spinae hold the pelvis and spine so that force transfers without the trunk collapsing.
Model licence · Z-Anatomy et BodyParts3D — CC-BY-SA 4.0

The movements it takes part in

The cuff is involved in every arm movement, but rarely as prime mover. In the vertical push, supraspinatus starts the lift and the other three keep the humerus centred while the deltoid supplies the force. In pulling movements, the lateral rotators accompany the movement of the shoulder blade.
It also works in everyday actions that require arm rotation: opening a door, combing your hair, putting on a jacket.

Synergists

  • The deltoid takes over from supraspinatus within the first few degrees of arm elevation.
  • Serratus anterior and the trapezius orient the shoulder blade, which moves the socket itself.
  • Teres major, often confused with teres minor, is not part of the cuff: it attaches to the lesser tubercle and acts with the latissimus dorsi.

Antagonists

  • Pectoralis major and the latissimus dorsi produce powerful medial rotation, which opposes the lateral rotators.
  • Subscapularis and infraspinatus are antagonists to one another, while being partners in centring.

What the 3D model simplifies

Limit
A sleeve seen from outside
The scene shows the four muscles as distinct volumes. In reality their tendons blend with the joint capsule into a continuous sheet, and the boundary between two neighbouring heads is often impossible to trace on a dissection.
Subscapularis poses a particular problem of representation: it lies flat on the face of the shoulder blade that looks towards the ribs. The model shows it as a volume, which helps locate it, but no observer could see it from behind the body. The bursae and the capsule, absent from the model, are nonetheless involved in a large share of shoulder pain.

Sources

Main sources

  • Standring S (2020). Gray's Anatomy: The Anatomical Basis of Clinical Practice, 42nd edition. Elsevier.
  • Neumann DA (2016). Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation, 3rd edition. Elsevier.
  • Kolber MJ, Beekhuizen KS, Cheng MS, Hellman MA (2010). Shoulder joint and muscle characteristics in the recreational weight training population. Journal of Strength and Conditioning Research.
Put it into practice in Shapier

Discover the face pull exercise

Open the face pull sheet in Shapier, a pull towards the face that works the shoulder's lateral rotators.
Discover the face pull exercise
Body Lab explains; Shapier lets you act and track.

Check my understanding

What is the main job of the rotator cuff ?
Which of these muscles is not part of the rotator cuff ?
Why is the shoulder both the most mobile joint in the body and a vulnerable one ?
Choose an answer

Read next

  • Deltoids
    The deltoid caps the shoulder with three heads pointing in different directions. It raises the arm in every direction, and its shape explains why the same shoulder changes function depending on the angle of the movement.
    With a 3D scene
  • Serratus anterior
    Serratus anterior links the ribs to the inner border of the shoulder blade and holds it flat against the ribcage. Without it the blade wings out and the arm cannot fully rise.
    With a 3D scene
  • Trapezius
    The trapezius links the skull and the spine to the shoulder girdle. Its three portions orient the shoulder blade, a condition without which the arm cannot rise fully.
    With a 3D scene

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Trust and method

Author
equipe-editoriale-shapier
Editorial review
Thanh Chau
Scientific review
Pending
Published on
August 2, 2026
Reviewed on August 2, 2026
Next review due August 2, 2027
Limits of this page
  • The subscapularis lies flat against the deep surface of the shoulder blade. The 3D scene shows it as a volume, but no observer could see it from behind, since the bone hides it.
  • The bursae and the joint capsule, which account for part of shoulder pain, are not represented.
  • This page describes an anatomy, not a symptom. Persistent shoulder pain calls for examination by a health professional.
Sources
  • Standring S (2020). Gray's Anatomy: The Anatomical Basis of Clinical Practice, 42nd edition. Elsevier.
  • Neumann DA (2016). Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation, 3rd edition. Elsevier.
  • Kolber MJ, Beekhuizen KS, Cheng MS, Hellman MA (2010). Shoulder joint and muscle characteristics in the recreational weight training population. Journal of Strength and Conditioning Research.
Educational content. Body Lab does not diagnose and does not replace professional advice.
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