Infraspinatus

• Infraspinatus:

  • Thick, triangular muscle, upper part is deep to trapezius, deltoid and the acromion process

  
• O (origin)

  • Medial 2/3 of the infraspinous fossa of scapular

  A) Infraspinatus

  
• R (direction)

  • Laterally and merge to a narrow tendon

  A) Infraspinatus

  
• I (insertions)

  • Middle facet on the greater tubercle of humerus
  • Bursa separates tendon from posterior part of glenohumeral joint

  A) Infraspinatus

  
• A (action)

  • Lateral rotation of glenohumeral joint

  A) Infraspinatus

  
• NS (nerve supply)

  • Suprascapular nerve (C4 - C6)

  A) Infraspinatus

  
• Infraspinatus - Function:

  • Stabilises the head of humerus in the glenoid fossa during glenohumeral movements with other rotator cuff muscles

  A) Infraspinatus