Pectoralis Major

• Pectoralis Major:

  • Thick triangular muscle, located upper half of the anterior chest wall

  
• Pectoralis Major - 2 heads:

  • Clavicular head
  • Sternal head
  • Two heads may be separated by a groove but are usually continuous
  • Form two layers as they insert into the humerus

  
• Pectoralis Major - Function:

  • Moves humerus forwards forcefully during punching, throwing and pushing movements
  • Climbing muscle so moves the trunk upwards when the arms are fixed overhead

  
• Sternal and Clavicular head:

  • both insert: Via a flat tendon to the lateral lip of the intertubercular groove
  • Sternal head (insertions): Forms the posterior lamina (layer) which passes upwards and behind the anterior lamina to the upper part of the groove
  • Clavicular head (insertions): Forms the anterior lamina which runs to the lower part of the groove
  • both NS: medial pectoral nerve (c8,t1) and lateral pectoral nerve (c5-c7)