Rotator Cuff Muscles: Attachments, Actions and Nerve Supply

By Dr Richard Miller, MBChB FRCS · Reviewed 1 October 2026

The rotator cuff is a group of four muscles, supraspinatus, infraspinatus, teres minor and subscapularis, that pass from the scapula to the tubercles of the humerus and blend with the shoulder capsule. They hold the humeral head in the shallow glenoid while deltoid and teres major move the arm.

Rotator Cuff Muscles · key facts

Origin: Supraspinous, infraspinous and subscapular fossae; lateral border of scapula
Insertion: Greater tubercle (supraspinatus, infraspinatus, teres minor); lesser tubercle (subscapularis)
Action: Stabilise the glenohumeral joint; abduction, lateral and medial rotation
Nerve supply: Suprascapular (C5, C6), axillary (C5, C6), upper and lower subscapular nerves (C5, C6)
Blood supply: Suprascapular, circumflex scapular and posterior circumflex humeral arteries

3D model of the rotator cuff muscles: long head of triceps brachii, supraspinatus, teres major and 1 more — 3D model showing the long head of triceps brachii, supraspinatus, teres major and 1 more.BodyParts3D, © The Database Center for Life Science licensed under CC Attribution 4.0 International

Attachments and actions

The rotator cuff muscles and the two other scapulohumeral muscles, deltoid and teres major, all run from the shoulder girdle to the humerus. The four cuff tendons fuse with the joint capsule to form a musculotendinous sleeve around the front, top and back of the glenohumeral joint. The cuff is deficient inferiorly, which is why the shoulder usually dislocates downwards and forwards.

Muscle	Origin	Insertion	Main action	Nerve
Supraspinatus	Supraspinous fossa	Superior facet of greater tubercle	Initiates abduction; works with deltoid throughout	Suprascapular
Infraspinatus	Infraspinous fossa	Middle facet of greater tubercle	Lateral rotation	Suprascapular
Teres minor	Upper two thirds of lateral border of scapula	Inferior facet of greater tubercle	Lateral rotation	Axillary
Subscapularis	Subscapular fossa	Lesser tubercle	Medial rotation	Upper and lower subscapular
Deltoid	Lateral third of clavicle, acromion, spine of scapula	Deltoid tuberosity	Abduction (middle fibres), flexion (anterior), extension (posterior)	Axillary
Teres major	Posterior surface near inferior angle	Medial lip of intertubercular sulcus	Adduction and medial rotation	Lower subscapular

All of these nerves carry fibres mainly from C5 and C6. The key role of the cuff is to compress the humeral head into the glenoid and depress it, so that deltoid lifts the arm rather than jamming the head up under the acromion.

Relations: spaces around teres minor and teres major

Three gaps between teres minor, teres major, the long head of triceps and the humerus transmit neurovascular structures from the axilla to the back of the shoulder and arm.

Space	Boundaries	Contents
Quadrangular space	Teres minor above, teres major below, long head of triceps medially, surgical neck of humerus laterally	Axillary nerve, posterior circumflex humeral artery
Triangular space	Teres minor above, teres major below, long head of triceps laterally	Circumflex scapular artery
Triangular interval	Teres major above, long head of triceps medially, humerus laterally	Radial nerve, profunda brachii artery

Supraspinatus passes under the coracoacromial arch, formed by the acromion, the coracoacromial ligament and the coracoid process. The subacromial bursa separates its tendon from the arch. The suprascapular nerve enters the supraspinous fossa through the suprascapular notch, beneath the superior transverse scapular ligament, while the suprascapular artery usually passes above the ligament. The nerve then winds around the spinoglenoid notch to reach infraspinatus.

Blood supply and innervation

The cuff is supplied by the suprascapular artery (supraspinatus and infraspinatus), the circumflex scapular artery (infraspinatus and teres minor) and the posterior circumflex humeral artery (teres minor and deltoid). Subscapularis receives branches of the subscapular artery. The supraspinatus tendon has a relatively poorly supplied zone just proximal to its insertion, often cited as one reason it degenerates.

The suprascapular nerve comes from the upper trunk of the brachial plexus. The axillary nerve and the upper and lower subscapular nerves come from the posterior cord.

Clinical relevance

The rotator cuff is the commonest source of shoulder pain in adults, and supraspinatus is the tendon most often affected.

Subacromial pain (impingement): the supraspinatus tendon and bursa are compressed under the coracoacromial arch. Pain typically occurs in a painful arc of mid-range abduction.
Cuff tears: usually degenerative, starting in supraspinatus near its insertion and extending backwards into infraspinatus. Acute tears follow falls or dislocation in older people.
Clinical tests: resisted abduction in the scapular plane with the thumb down (Jobe's empty-can test) for supraspinatus; resisted lateral rotation and the lag sign for infraspinatus and teres minor; lift-off and belly-press tests for subscapularis.
Axillary nerve injury: from anterior dislocation or a surgical neck fracture. It weakens deltoid and teres minor and numbs the skin over the lower deltoid, the regimental badge area.
Suprascapular nerve entrapment: at the suprascapular notch it weakens both supraspinatus and infraspinatus; at the spinoglenoid notch it affects infraspinatus alone.

How it is examined

On a cadaveric spotter, in an OSPE and in MRCS Part B anatomy.

On a posterior shoulder prosection, the muscle above the spine of the scapula is supraspinatus and the one below it is infraspinatus. Teres minor lies along the lateral border above teres major.
A pin on the muscle passing in front of the long head of triceps to the medial lip of the intertubercular sulcus is teres major, not a cuff muscle. Teres major passes anterior to the long head of triceps; teres minor passes posterior to it.
The nerve emerging through the quadrangular space with the posterior circumflex humeral artery is the axillary nerve. Expect the follow-up on the regimental badge sign.
Know which cuff muscle inserts on the lesser tubercle (subscapularis) and which is supplied by the axillary nerve (teres minor).
Examiners often ask which muscle initiates abduction and which takes over: supraspinatus starts it, deltoid continues, and trapezius and serratus anterior rotate the scapula beyond about 90 degrees.

Key points

The rotator cuff is supraspinatus, infraspinatus, teres minor and subscapularis.
Three insert on the greater tubercle; subscapularis inserts on the lesser tubercle.
The cuff stabilises the humeral head in the glenoid so deltoid can abduct the arm.
Suprascapular, axillary and subscapular nerves supply the group, mainly from C5 and C6.
The quadrangular space transmits the axillary nerve and posterior circumflex humeral artery.
Supraspinatus is the tendon most often impinged and torn.

Common questions

What are the four rotator cuff muscles?

The four rotator cuff muscles are supraspinatus, infraspinatus, teres minor and subscapularis, often remembered as SITS. All arise from the scapula and insert close to the humeral head, blending with the capsule of the shoulder joint. Supraspinatus, infraspinatus and teres minor attach to the greater tubercle; subscapularis attaches to the lesser tubercle at the front of the humerus.

Which rotator cuff muscle is most commonly torn?

Supraspinatus is the most commonly torn rotator cuff muscle. Its tendon passes through the narrow space beneath the acromion and coracoacromial ligament, where it is compressed during overhead movements, and it degenerates with age near its insertion on the greater tubercle. Tears usually begin there and may extend backwards into infraspinatus. Weak, painful abduction is the typical finding.

What nerve supplies the rotator cuff?

Three nerves supply the rotator cuff. The suprascapular nerve supplies supraspinatus and infraspinatus. The axillary nerve supplies teres minor. The upper and lower subscapular nerves supply subscapularis. All carry fibres mainly from C5 and C6. The suprascapular nerve comes from the upper trunk of the brachial plexus, and the others come from the posterior cord.

What is the quadrangular space?

The quadrangular space is a gap at the back of the shoulder bounded by teres minor above, teres major below, the long head of triceps medially and the surgical neck of the humerus laterally. The axillary nerve and posterior circumflex humeral artery pass through it to reach deltoid and teres minor. Fibrous bands or hypertrophied muscle can compress these structures here.

References

Gray's Anatomy: The Anatomical Basis of Clinical Practice. Standring S (ed). Elsevier. 42nd edition, 2020.
Moore's Clinically Oriented Anatomy. Moore KL, Dalley AF, Agur AMR. Wolters Kluwer. 9th edition, 2022.
Gray's Anatomy for Students. Drake RL, Vogl AW, Mitchell AWM. Elsevier.