Pectoralis Major Anatomy

Pectoralis Major Muscle

Pectoralis Major Clavicular Head

Origin: Anterior surface of the medial half of the clavicle
Insertion: Lateral lip of the bicipital groove of the humerus and the anterior lip of the deltoid tuberosity
Actions: Flexion, adduction, internal rotation of the arm at the shoulder
Innervation: Medial pectoral nerve (C8, T1) and lateral pectoral nerve (C5, 6, 7 )
Blood Supply: Pectoral branches from the thoraco-acromial artery

Primary Actions of the Pectoralis Major-Clavicular Head

1. Flexion of the arm at the shoulder

Agonists:

  • Deltoid (anterior part)
  • Biceps Brachii
  • Coracobrachialis

Antagonists:

  • Deltoid (posterior fibers)
  • Triceps Brachii (long head)
  • Latissimus Dorsi
  • Pectoralis Major (sternal head)
  • Teres Major

2. Adduction of the arm at the shoulder

Agonists:

  • Latissimus Dorsi
  • Teres Major
  • Pectoralis Major (sternal head)
  • Triceps Brachii

Antagonists:

  • Deltoid (middle fibers)
  • Supraspinatus

Coracobrachialis and teres minor assist with adduction of the arm at the shoulder.

3. Internal rotation of the arm at the shoulder

Agonists:

  • Latissimus Dorsi
  • Subscapularis
  • Deltoid (anterior fibers)
  • Pectoralis Major (sternal head)
  • Teres Major

Antagonists:

  • Infraspinatus
  • Teres Minor
  • Deltoid (posterior part)

Advertisement




Pectoralis Major Sternal Head

Origin: Lateral aspects of the manubrium and body of the sternum, the upper six costal cartilages and the aponeurosis of external abdominal oblique
Insertion: Lateral lip of the bicipital groove of the humerus and anterior lip of the deltoid tuberosity
Actions: Adduction, internal rotation and extension of the arm at the shoulder
Innervation: Medial pectoral nerve (C8, T1) and lateral pectoral nerve (C5, 6, 7 )
Blood Supply: Pectoral branches from the thoraco-acromial artery

Primary Actions of the Pectoralis Major-Sternal Head

1. Adduction of the arm at the shoulder
Agonists:

  • Latissimus dorsi
  • Teres major
  • Pectoralis major (clavicular head)
  • Triceps brachii (long head)

Antagonists:

  • Deltoid (middle)
  • Supraspinatus

Coracobrachialis and teres minor assist with adduction of the arm at the shoulder.

2. Internal rotation of the arm at the shoulder

  Agonists:

  • Latissimus dorsi
  • Subscapularis
  • Deltoid (anterior)
  • Pectoralis major (clavicular head)
  • Teres major

  Antagonists:

  • Infraspinatus
  • Teres minor
  • Deltoid (posterior part)

3. Extension of the arm at the shoulder

Agonists:

  • Latissimus dorsi
  • Deltoid (posterior)
  • Triceps brachii (long head)
  • Teres major

Antagonist:

  • Deltoid (anterior part)
  • Biceps brachii
  • Coracobrachialis
  • Pectoralis major (clavicular head)