Muscles of the Scapula and Humerus

Muscles

Supraspinatus

• Origin: Supraspinatus fossa of the scapula.
• Insertion: Greater tubercle of the humerus.
• Action: Abducts the arm; slight lateral rotation.

Infraspinatus

• Origin: Infraspinatus fossa of the scapula.
• Insertion: Greater tubercle of the humerus (posterior to the supraspinatus).
• Action: Laterally rotates the arm; slight adduction.

Subscapularis

• Origin: Subscapular fossa of the scapula.
• Insertion: Lesser tubercle of the humerus.
• Action: Medially rotates the arm.

Teres Minor

• Origin: Axillary border of the scapula.
• Insertion: Greater tubercle of the humerus (posterior to the infraspinatus).
• Action: Laterally rotates the arm.

Teres Major

• Origin: Dorsal surface of the inferior angle of the scapula.
• Insertion: Lesser tubercle of the humerus.
• Action: Adducts, extends, and medially rotates the arm.