Muscles of the Shoulder/Upper Arm

Movements of the Humerus (upper arm at the shoulder)
• Movements of the humerus:
– – – – – Flexion and Extension Abduction and Adduction External and Internal Rotation Horizontal flexion or Horizontal adduction Horizontal extension or Horizontal abduction

Flexion and Extension

Abduction and Adduction

External and Internal Rotation

Horizonal flexion or adduction

Horizontal extension or abduction

Muscles of the Shoulder/Upper Arm
• Anterior:
– Pectoralis major, Coracobrachialis, Subscapularis

Pectoralis major
• Origin:
– Clavicle, sternum, and costal cartilage of ribs

• Insertion:
– Near the intertubercular groove of the humerus

• Actions:
– Flexion, horizontal flexion, internal rotation, adduction
• Used in bench press, pushup, pull-ups, throwing, tennis serves

Pectoralis Major

Coracobrachialis
• Origin:
– Coracoid process of scapula

• Insertion:
– Humerus (medial)

• Actions:
– Flexion, adduction, horizontal flexion – Primarily an assisting muscle

Coracobrachialis

Subscapularis
• Origin:
– Subscapular fossa of scapula

• Insertion:
– Lesser tubercle of humerus

• Actions:
– Internal rotation, extension and adduction

Subscapularis

Muscles of the Shoulder/Upper Arm
• Superior:
– Deltoid, Supraspinatus

Deltoid
• Origin:
– Clavicle, scapula

• Insertion:
– Deltoid tuberosity of humerus

• Actions:
– Abduction – Anterior deltoid: horizontal flexion, internal rotation – Posterior deltoid: horizontal extension and external rotation

Deltoid

Muscles of the Shoulder/Upper Arm
• Posterior:
– Latissimus dorsi, Teres major and minor, Infraspinatus

Latissimus Dorsi
• Origin:
– Vertebrae, sacrum, ilium

• Insertion:
– Near the intertubercular groove of humerus

• Actions:
– Extension (prime mover), adduction, internal