Muscles of the Anterior Thorax

• Pectoralis Minor - Origin & Insertion


  flat, thin muscle directly beneath + obscured by pectoralis major

  origin - anterior surfaces of ribs 3-5

  insertion - coracoid process of scapula

  
• Pectoralis Minor - Action


  w ribs fixed, pulls scapula forward + downward

  w scapula fixed, pulls rib cage superiorly
• Serratus Anterior


  fan-shaped muscle

  lies deep to the scapula

  deep + inferior to pectoral muscles on lateral rib cage

  origin - by a series of muscle branches from ribs 1-8

  insertion - entire anterior surface of medial border of scapula

  
• Serratus Anterior - Action


  rotates scapula so its inferior angle moves laterally + upward

  prime mover to protract + hold scapula against chest wall

  raises point of shoulder

  important role in abducting + raising arm + in horizontal arm movements (pushing + punching, boxer muscle)
• Subclavius 


  small cylindrical muscle extending from rib 1 to clavicle

  origin - costal cartilage of rib 1

  insertion - groove on inferior surface of clavicle

  action - help stabilise + depress pectoral girdle