Shoulder Muscle Anatomy

 

Courtesy- Dr Nabil

 

 

The shoulder joint

• Formed by the scapula (shoulder blade) and the humerus.

Shoulder function

• Movement and stability are provided by the muscles surrounding the shoulder joint and scapula.

Posterior Shoulder Muscles

Supraspinatus

• Initiates shoulder abduction.
• Stabilizes the glenohumeral joint.

Infraspinatus

• Primary external rotator of the shoulder.
• Provides dynamic stability.

Teres Minor

• Assists external rotation.
• Part of the rotator cuff.

Teres Major

• Adducts the shoulder.
• Internally rotates the shoulder.
• Extends the shoulder.

Deltoid

• Main abductor of the shoulder.
• Anterior fibers flex and internally rotate.
• Posterior fibers extend and externally rotate.