📓 Rotator Cuff

Brian Lee
Review Pending

Function

Stabilizes the shoulder joint.

Rotates and elevates the arm.

Muscles

1. 💪 Infraspinatus
2. 💪 Subscapularis
3. 💪 Supraspinatus
4. 💪 Teres Minor

Origins

All four rotator‑cuff muscles originate on the scapula:

• Supraspinatus
  • Originates from the supraspinous fossa of the scapula
• Infraspinatus
  • Originates from the infraspinous fossa of the scapula
• Teres minor
  • Originates from the lateral border of the scapula
• Subscapularis
  • Originates from the subscapular fossa (anterior surface) of the scapula

Each muscle spans from the scapula to attach at the proximal (upper) end of the 🦴 humerus—the long bone of the upper arm—forming the musculotendinous “cuff” that stabilizes the glenohumeral (shoulder) joint.

Insertions

Of the four rotator‐cuff muscles, only subscapularis inserts on the anterior surface of the 🦴 humerus:

• Subscapularis
  • Insertion: Lesser tubercle of the 🦴 humerus (anterior aspect)
  • Action: Medially rotates and adducts the 🦴 humerus

The other three insert on the greater tubercle, which lies more posterior‑lateral:

• Supraspinatus
  • Insertion: Superior facet of the greater tubercle
  • Action: Abducts the 🦴 humerus
• Infraspinatus
  • Insertion: Middle facet of the greater tubercle
  • Action: Laterally rotates the 🦴 humerus
• Teres minor
  • Insertion: Inferior facet of the greater tubercle
  • Action: Laterally rotates and assists in adduction of the 🦴 humerus

Actions

• Subscapularis
  • Action: Medially rotates and adducts the 🦴 humerus
• Supraspinatus
  • Action: Abducts the 🦴 humerus
• Infraspinatus
  • Action: Laterally rotates the 🦴 humerus
• Teres minor
  • Action: Laterally rotates and assists in adduction of the 🦴 humerus

References

• 🦴 Humerus