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Pectoralis major

Contents

Anatomy

General information

  • This section is strictly limited to anatomy, you might be looking for clinical relevant information which is found under the clinical chapters -- muscles section, click here to go to that page

Position

  • Superficial

Origin

  • Clavicula
    • Medial 1/2
  • Costal cartilage 1-7th ribs
  • Sternum
  • Aponeurosis of the external oblique

Insertion

  • Crista tuberculi major humerus

Main function

  • Shoulder
    • Adduction
    • Medial rotation
    • Flexion

Secondary function

  • Shoulder
    • Extension
    • Abduction
  • Scapula
    • Depression
    • Protraction
  • Trunk
    • Elevation
      • When arm/scapula is fixated
    • Lateral deviation
    • Ipisilateral rotation

Nerve innervation

  • Segmental
    • C5-Th1
  • Peripheral
    • Medial pectoral nerve
    • Lateral pectoral nerve

Arterial supply

  • Pectoral branch of thoracoacromial artery
  • Posterior intercostal artery
  • Lateral thoracal artery

Palpation

  • Patient position
    • Standing
  • The muscle is superficial and covers a greater area, and is therefore easy to palpate
  • Have the patient lift the arm to 90° abduction of the shoulder joint
  • Palpate the muscle belly of pectoralis major
  • Give resistance to the patient in direction of abduction, so the patient is giving force towards adduction
    • Feel for the contraction in the muscle

Muscle length test for sternal part of pectoralis major

  • Patient position
    • Supine
  • Ask the patient to flex his/her knees, while the lower back is held flat onto the surface
  • Place the patient's arms in 135° abduction while the elbow is extended, and the shoulder in a laterally rotated position
  • If the arm is held in level with the bench while the lower back is flat and in full contact with the bench, the muscle is considered to be of appropriate length

Muscle length test for clavicular part of pectoralis major

  • Patient position
    • Supine
  • Ask the patient to flex the knees while the lower back is in full contact with the bench
  • Place the arm of the patient in a 90° abduction while the elbow is extended, the shoulder should be in a laterally rotated position
  • If the arm is in level with the bench while the lower back is flat and in contact with the bench, the muscle is considered to be of sufficient length

Strength test for sternal part of pectoralis major

  • Patient position
    • Supine
  • The patient hold the arm in flexion in front of the body while the elbow is extended, the arm is rotated somewhat in a medial position
  • The patient places the arm in a somewhat adducted position
  • Fixate the patient's pelvis from the opposite side to stabilize the patient during testing
  • Give resistance to the patient's lower arm in a lateral and cranial direction so that the patient is giving force towards adduction and extension

Strength test for clavicular part of pectoralis major

  • Patient position
    • Supine
  • The patient holds the arm in a 90° flexion of the shoulder joint while the elbow is extended and the arm somewhat rotated into medial rotation
  • The patient adducts the arm somewhat from this position
  • Give resistance to the patient's lower arm in a horizontal abduction direction so that the patient gives force towards adduction