estrinsic thorax muscles (pectoralis region)

Question 1

pectoralis major

Answer 1

• origin: sternal half of clavicle, upper half of sternum, aponeurosis of external abs oblique
• insertion: crest of the greater tubercle of the humerus
• action: flexes and adducts the arm, medially rotates the arm
  togetherwith lats and teres major can extend flexed humerus to the side of the trunk

Question 2

pectoralis minor

Answer 2

• origin: ribs 3-5
• insertion: coracoid process of scapula
• action: protracts scapula

Question 3

subclavius

Answer 3

• origin: first rib and its cartilage
• insertion: inferior surface of the clavicle
• action: depresses clavicle

Question 4

serratus anterior

Answer 4

• origin: ribs 1-8 or 9
• insertion: medial border of the scapula on its costal (deep) surface
• action: protraction, hold scapula on thoracic wall, Rotates scapula (draws inferiorly angle laterally)