4. Accessory Thoracic Muscles

Pectoralis Major Origin (Clavicular)

anteiror surface clavicle; medial half

Pectoralis Major Origin (Sternoclavicular)

anterior sternum, costal cartilage 1-7; rib 6

Pectoralis Major Insertion

lateral border intertubercular sulcus of humerus

Pectoralis Major Action

- flexion of humerus

- adduction of humerus

- medial rotation humerus

- (Clav) flexion of extended arm

- (Stern) extension of flexed arm

Pectoralis Major Innervation

medial & lateral pectoral N

Pectoralis Minor Origin

anterior surface ribs 3-5

Pectoralis Minor Insertion

coracoid process scapula

Pectoralis Minor Innervation

medial pectoral N

Pectoralis Minor Action

protract/abduct scapula; depress scapula

Subclavius Origin

rib 1 (between costal cartilage & bony portion)

Subclavius Insertion

inferior surface clavicle

Subclavius Action

N to subclavius

Subclavius Innervation

stabilize sternoclavicular joint; medial depression of clavicle

Serratus Anterior Origin

lateral surfaces ribs 8-9

Serratus Anterior Insertion

medial border scapula; anterior surface

Serratus Anterior Action

protraction, rotation, fixing of scapula

Serratus Anterior Innervation

long thoracic N

Serratus Posterior Superior Origin

spinous processes C7-T3; lower ligamentum nuchae; supraspinous ligament

Serratus Posterior Insertion

upper border ribs 2-5

Serratus Posterior Action

anterior rami upper thoracic N

Serratus Posterior Superior Innervation

ELEVATE RIBS 2-5

Serratus Posterior Inferior Origin

Spinour process T11-L3; Supraspinous ligament

Serratus Posterior Inferior Insertion

lower border ribs 9-12

Serratus Posterior Inferior Action

depress ribs; tie down lower ribs in diaphragm contraction

Serratus Posterior Inferior Innervation

Anterior rami of lower thoracic N

Levatores Costarum Origin

Transverse processes C7-T11

Levatores Costarum Insertion

Rib below vertebra of origin

Levatores Costarum Innervation

posterior rami spinal N

Levatores Costarum Action

elevated ribs